Per-column collation support

This adds collation support for columns and domains, a COLLATE clause
to override it per expression, and B-tree index support.

Peter Eisentraut
reviewed by Pavel Stehule, Itagaki Takahiro, Robert Haas, Noah Misch

config/c-library.m4

@@ -297,3 +297,32 @@ int main()
 ])dnl AC_CACHE_VAL
 AC_MSG_RESULT([$pgac_cv_printf_arg_control])
 ])# PGAC_FUNC_PRINTF_ARG_CONTROL
+
+
+# PGAC_TYPE_LOCALE_T
+# ------------------
+# Check for the locale_t type and find the right header file.  Mac OS
+# X needs xlocale.h; standard is locale.h, but glibc also has an
+# xlocale.h file that we should not use.
+#
+AC_DEFUN([PGAC_TYPE_LOCALE_T],
+[AC_CACHE_CHECK([for locale_t], pgac_cv_type_locale_t,
+[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+[#include <locale.h>
+locale_t x;],
+[])],
+[pgac_cv_type_locale_t=yes],
+[AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+[#include <xlocale.h>
+locale_t x;],
+[])],
+[pgac_cv_type_locale_t='yes (in xlocale.h)'],
+[pgac_cv_type_locale_t=no])])])
+if test "$pgac_cv_type_locale_t" != no; then
+  AC_DEFINE(HAVE_LOCALE_T, 1,
+            [Define to 1 if the system has the type `locale_t'.])
+fi
+if test "$pgac_cv_type_locale_t" = 'yes (in xlocale.h)'; then
+  AC_DEFINE(LOCALE_T_IN_XLOCALE, 1,
+            [Define to 1 if `locale_t' requires <xlocale.h>.])
+fi])])# PGAC_HEADER_XLOCALE

configure

@@ -16830,6 +16830,114 @@ _ACEOF
   fi
 
 
+{ $as_echo "$as_me:$LINENO: checking for locale_t" >&5
+$as_echo_n "checking for locale_t... " >&6; }
+if test "${pgac_cv_type_locale_t+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <locale.h>
+locale_t x;
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  pgac_cv_type_locale_t=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <xlocale.h>
+locale_t x;
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  pgac_cv_type_locale_t='yes (in xlocale.h)'
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	pgac_cv_type_locale_t=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:$LINENO: result: $pgac_cv_type_locale_t" >&5
+$as_echo "$pgac_cv_type_locale_t" >&6; }
+if test "$pgac_cv_type_locale_t" != no; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_LOCALE_T 1
+_ACEOF
+
+fi
+if test "$pgac_cv_type_locale_t" = 'yes (in xlocale.h)'; then
+
+cat >>confdefs.h <<\_ACEOF
+#define LOCALE_T_IN_XLOCALE 1
+_ACEOF
+
+fi
+
 { $as_echo "$as_me:$LINENO: checking for struct cmsgcred" >&5
 $as_echo_n "checking for struct cmsgcred... " >&6; }
 if test "${ac_cv_type_struct_cmsgcred+set}" = set; then

configure.in

@@ -1118,6 +1118,8 @@ AC_TYPE_INTPTR_T
 AC_TYPE_UINTPTR_T
 AC_TYPE_LONG_LONG_INT
 
+PGAC_TYPE_LOCALE_T
+
 AC_CHECK_TYPES([struct cmsgcred, struct fcred, struct sockcred], [], [],
 [#include <sys/param.h>
 #include <sys/types.h>

contrib/btree_gin/btree_gin.c

@@ -7,6 +7,7 @@
 
 #include "fmgr.h"
 #include "access/skey.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
 #include "utils/bytea.h"
 #include "utils/cash.h"
@@ -120,8 +121,9 @@ gin_compare_prefix_##type(PG_FUNCTION_ARGS)									\
 	int32		res,														\
 				cmp;														\
 																			\
-	cmp = DatumGetInt32(DirectFunctionCall2(								\
+	cmp = DatumGetInt32(DirectFunctionCall2WithCollation(					\
 				TypeInfo_##type.typecmp,									\
+				DEFAULT_COLLATION_OID,										\
 				(data->strategy == BTLessStrategyNumber ||					\
 				 data->strategy == BTLessEqualStrategyNumber)				\
 				 ? data->datum : a,											\

contrib/btree_gist/btree_text.c

@@ -3,6 +3,7 @@
  */
 #include "btree_gist.h"
 #include "btree_utils_var.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
 
 /*
@@ -32,37 +33,37 @@ Datum		gbt_text_same(PG_FUNCTION_ARGS);
 static bool
 gbt_textgt(const void *a, const void *b)
 {
-	return (DatumGetBool(DirectFunctionCall2(text_gt, PointerGetDatum(a), PointerGetDatum(b))));
+	return (DatumGetBool(DirectFunctionCall2WithCollation(text_gt, DEFAULT_COLLATION_OID, PointerGetDatum(a), PointerGetDatum(b))));
 }
 
 static bool
 gbt_textge(const void *a, const void *b)
 {
-	return (DatumGetBool(DirectFunctionCall2(text_ge, PointerGetDatum(a), PointerGetDatum(b))));
+	return (DatumGetBool(DirectFunctionCall2WithCollation(text_ge, DEFAULT_COLLATION_OID, PointerGetDatum(a), PointerGetDatum(b))));
 }
 
 static bool
 gbt_texteq(const void *a, const void *b)
 {
-	return (DatumGetBool(DirectFunctionCall2(texteq, PointerGetDatum(a), PointerGetDatum(b))));
+	return (DatumGetBool(DirectFunctionCall2WithCollation(texteq, DEFAULT_COLLATION_OID, PointerGetDatum(a), PointerGetDatum(b))));
 }
 
 static bool
 gbt_textle(const void *a, const void *b)
 {
-	return (DatumGetBool(DirectFunctionCall2(text_le, PointerGetDatum(a), PointerGetDatum(b))));
+	return (DatumGetBool(DirectFunctionCall2WithCollation(text_le, DEFAULT_COLLATION_OID, PointerGetDatum(a), PointerGetDatum(b))));
 }
 
 static bool
 gbt_textlt(const void *a, const void *b)
 {
-	return (DatumGetBool(DirectFunctionCall2(text_lt, PointerGetDatum(a), PointerGetDatum(b))));
+	return (DatumGetBool(DirectFunctionCall2WithCollation(text_lt, DEFAULT_COLLATION_OID, PointerGetDatum(a), PointerGetDatum(b))));
 }
 
 static int32
 gbt_textcmp(const bytea *a, const bytea *b)
 {
-	return DatumGetInt32(DirectFunctionCall2(bttextcmp, PointerGetDatum(a), PointerGetDatum(b)));
+	return DatumGetInt32(DirectFunctionCall2WithCollation(bttextcmp, DEFAULT_COLLATION_OID, PointerGetDatum(a), PointerGetDatum(b)));
 }
 
 static gbtree_vinfo tinfo =

contrib/btree_gist/btree_utils_var.c

@@ -8,6 +8,7 @@
 #include <float.h>
 
 #include "btree_utils_var.h"
+#include "catalog/pg_collation.h"
 #include "utils/pg_locale.h"
 #include "utils/builtins.h"
 #include "utils/rel.h"
@@ -156,7 +157,7 @@ gbt_bytea_pf_match(const bytea *pf, const bytea *query, const gbtree_vinfo *tinf
 
 		if (tinfo->eml > 1)
 		{
-			out = (varstr_cmp(q, nlen, n, nlen) == 0);
+			out = (varstr_cmp(q, nlen, n, nlen, DEFAULT_COLLATION_OID) == 0);
 		}
 		else
 		{

contrib/citext/citext.c

@@ -18,7 +18,7 @@ PG_MODULE_MAGIC;
  *		====================
  */
 
-static int32 citextcmp(text *left, text *right);
+static int32 citextcmp(text *left, text *right, Oid collid);
 extern Datum citext_cmp(PG_FUNCTION_ARGS);
 extern Datum citext_hash(PG_FUNCTION_ARGS);
 extern Datum citext_eq(PG_FUNCTION_ARGS);
@@ -42,17 +42,18 @@ extern Datum citext_larger(PG_FUNCTION_ARGS);
  * Returns int32 negative, zero, or positive.
  */
 static int32
-citextcmp(text *left, text *right)
+citextcmp(text *left, text *right, Oid collid)
 {
 	char	   *lcstr,
 			   *rcstr;
 	int32		result;
 
-	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left));
-	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right));
+	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), collid);
+	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), collid);
 
 	result = varstr_cmp(lcstr, strlen(lcstr),
-						rcstr, strlen(rcstr));
+						rcstr, strlen(rcstr),
+						collid);
 
 	pfree(lcstr);
 	pfree(rcstr);
@@ -75,7 +76,7 @@ citext_cmp(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	int32		result;
 
-	result = citextcmp(left, right);
+	result = citextcmp(left, right, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(left, 0);
 	PG_FREE_IF_COPY(right, 1);
@@ -92,7 +93,7 @@ citext_hash(PG_FUNCTION_ARGS)
 	char	   *str;
 	Datum		result;
 
-	str = str_tolower(VARDATA_ANY(txt), VARSIZE_ANY_EXHDR(txt));
+	str = str_tolower(VARDATA_ANY(txt), VARSIZE_ANY_EXHDR(txt), PG_GET_COLLATION());
 	result = hash_any((unsigned char *) str, strlen(str));
 	pfree(str);
 
@@ -121,8 +122,8 @@ citext_eq(PG_FUNCTION_ARGS)
 
 	/* We can't compare lengths in advance of downcasing ... */
 
-	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left));
-	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right));
+	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), PG_GET_COLLATION());
+	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), PG_GET_COLLATION());
 
 	/*
 	 * Since we only care about equality or not-equality, we can avoid all the
@@ -151,8 +152,8 @@ citext_ne(PG_FUNCTION_ARGS)
 
 	/* We can't compare lengths in advance of downcasing ... */
 
-	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left));
-	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right));
+	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), PG_GET_COLLATION());
+	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), PG_GET_COLLATION());
 
 	/*
 	 * Since we only care about equality or not-equality, we can avoid all the
@@ -177,7 +178,7 @@ citext_lt(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = citextcmp(left, right) < 0;
+	result = citextcmp(left, right, PG_GET_COLLATION()) < 0;
 
 	PG_FREE_IF_COPY(left, 0);
 	PG_FREE_IF_COPY(right, 1);
@@ -194,7 +195,7 @@ citext_le(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = citextcmp(left, right) <= 0;
+	result = citextcmp(left, right, PG_GET_COLLATION()) <= 0;
 
 	PG_FREE_IF_COPY(left, 0);
 	PG_FREE_IF_COPY(right, 1);
@@ -211,7 +212,7 @@ citext_gt(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = citextcmp(left, right) > 0;
+	result = citextcmp(left, right, PG_GET_COLLATION()) > 0;
 
 	PG_FREE_IF_COPY(left, 0);
 	PG_FREE_IF_COPY(right, 1);
@@ -228,7 +229,7 @@ citext_ge(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = citextcmp(left, right) >= 0;
+	result = citextcmp(left, right, PG_GET_COLLATION()) >= 0;
 
 	PG_FREE_IF_COPY(left, 0);
 	PG_FREE_IF_COPY(right, 1);
@@ -251,7 +252,7 @@ citext_smaller(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	text	   *result;
 
-	result = citextcmp(left, right) < 0 ? left : right;
+	result = citextcmp(left, right, PG_GET_COLLATION()) < 0 ? left : right;
 	PG_RETURN_TEXT_P(result);
 }
 
@@ -264,6 +265,6 @@ citext_larger(PG_FUNCTION_ARGS)
 	text	   *right = PG_GETARG_TEXT_PP(1);
 	text	   *result;
 
-	result = citextcmp(left, right) > 0 ? left : right;
+	result = citextcmp(left, right, PG_GET_COLLATION()) > 0 ? left : right;
 	PG_RETURN_TEXT_P(result);
 }

contrib/citext/citext.sql.in

@@ -52,7 +52,8 @@ CREATE TYPE citext (
     STORAGE        = extended,
     -- make it a non-preferred member of string type category
     CATEGORY       = 'S',
-    PREFERRED      = false
+    PREFERRED      = false,
+    COLLATABLE     = true
 );
 
 --

contrib/ltree/lquery_op.c

@@ -7,6 +7,7 @@
 
 #include <ctype.h>
 
+#include "catalog/pg_collation.h"
 #include "utils/array.h"
 #include "utils/formatting.h"
 #include "ltree.h"
@@ -90,8 +91,8 @@ bool
 int
 ltree_strncasecmp(const char *a, const char *b, size_t s)
 {
-	char	   *al = str_tolower(a, s);
-	char	   *bl = str_tolower(b, s);
+	char	   *al = str_tolower(a, s, DEFAULT_COLLATION_OID);
+	char	   *bl = str_tolower(b, s, DEFAULT_COLLATION_OID);
 	int			res;
 
 	res = strncmp(al, bl, s);

doc/src/sgml/catalogs.sgml

@@ -103,6 +103,11 @@
       <entry>check constraints, unique constraints, primary key constraints, foreign key constraints</entry>
      </row>
 
+     <row>
+      <entry><link linkend="catalog-pg-collation"><structname>pg_collation</structname></link></entry>
+      <entry>collations (locale information)</entry>
+     </row>
+
      <row>
       <entry><link linkend="catalog-pg-conversion"><structname>pg_conversion</structname></link></entry>
       <entry>encoding conversion information</entry>
@@ -1113,6 +1118,16 @@
       </entry>
      </row>
 
+     <row>
+      <entry><structfield>attcollation</structfield></entry>
+      <entry><type>oid</type></entry>
+      <entry><literal><link linkend="catalog-pg-collation"><structname>pg_collation</structname></link>.oid</literal></entry>
+      <entry>
+       The defined collation of the column, zero if the column does
+       not have a collatable type.
+      </entry>
+     </row>
+
      <row>
       <entry><structfield>attacl</structfield></entry>
       <entry><type>aclitem[]</type></entry>
@@ -2050,6 +2065,76 @@
 
  </sect1>
 
+ <sect1 id="catalog-pg-collation">
+  <title><structname>pg_collation</structname></title>
+
+  <indexterm zone="catalog-pg-collation">
+   <primary>pg_collation</primary>
+  </indexterm>
+
+  <para>
+   The catalog <structname>pg_collation</structname> describes the
+   available collations, which are essentially mappings from an SQL
+   name to operating system locale categories.
+   See <xref linkend="locale"> for more information.
+  </para>
+
+  <table>
+   <title><structname>pg_collation</> Columns</title>
+
+   <tgroup cols="4">
+    <thead>
+     <row>
+      <entry>Name</entry>
+      <entry>Type</entry>
+      <entry>References</entry>
+      <entry>Description</entry>
+     </row>
+    </thead>
+
+    <tbody>
+     <row>
+      <entry><structfield>collname</structfield></entry>
+      <entry><type>name</type></entry>
+      <entry></entry>
+      <entry>Collation name (unique per namespace and encoding)</entry>
+     </row>
+
+     <row>
+      <entry><structfield>collnamespace</structfield></entry>
+      <entry><type>oid</type></entry>
+      <entry><literal><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.oid</literal></entry>
+      <entry>
+       The OID of the namespace that contains this collation
+      </entry>
+     </row>
+
+     <row>
+      <entry><structfield>collencoding</structfield></entry>
+      <entry><type>int4</type></entry>
+      <entry></entry>
+      <entry>Encoding to which the collation is applicable</entry>
+     </row>
+
+     <row>
+      <entry><structfield>collcollate</structfield></entry>
+      <entry><type>name</type></entry>
+      <entry></entry>
+      <entry>LC_COLLATE for this collation object</entry>
+     </row>
+
+     <row>
+      <entry><structfield>collctype</structfield></entry>
+      <entry><type>name</type></entry>
+      <entry></entry>
+      <entry>LC_CTYPE for this collation object</entry>
+     </row>
+    </tbody>
+   </tgroup>
+  </table>
+
+ </sect1>
+
  <sect1 id="catalog-pg-conversion">
   <title><structname>pg_conversion</structname></title>
 
@@ -3125,6 +3210,16 @@
       </entry>
      </row>
 
+     <row>
+      <entry><structfield>indcollation</structfield></entry>
+      <entry><type>oidvector</type></entry>
+      <entry><literal><link linkend="catalog-pg-collation"><structname>pg_collation</structname></link>.oid</literal></entry>
+      <entry>
+       For each column in the index key, this contains the OID of the
+       collation to use for the index.
+      </entry>
+     </row>
+
      <row>
       <entry><structfield>indclass</structfield></entry>
       <entry><type>oidvector</type></entry>
@@ -5866,6 +5961,21 @@
        </para></entry>
      </row>
 
+     <row>
+      <entry><structfield>typcollation</structfield></entry>
+      <entry><type>oid</type></entry>
+      <entry><literal><link linkend="catalog-pg-collation"><structname>pg_collation</structname></link>.oid</literal></entry>
+      <entry><para>
+       <structfield>typcollation</structfield> specifies the collation
+       of the type.  If a type does not support collations, this will
+       be zero, collation analysis at parse time is skipped, and
+       the use of <literal>COLLATE</literal> clauses with the type is
+       invalid.  A base type that supports collations will have
+       <symbol>DEFAULT_COLLATION_OID</symbol> here.  A domain can have
+       another collation OID, if one was defined for the domain.
+      </para></entry>
+     </row>
+
      <row>
       <entry><structfield>typdefaultbin</structfield></entry>
       <entry><type>pg_node_tree</type></entry>

doc/src/sgml/charset.sgml

@@ -304,6 +304,170 @@ initdb --locale=sv_SE
  </sect1>
 
 
+ <sect1 id="collation">
+  <title>Collation Support</title>
+
+  <para>
+   The collation support allows specifying the sort order and certain
+   other locale aspects of data per column or per operation at run
+   time.  This alleviates the problem that the
+   <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol> settings
+   of a database cannot be changed after its creation.
+  </para>
+
+  <note>
+   <para>
+    The collation support feature is currently only known to work on
+    Linux/glibc and Mac OS X platforms.
+   </para>
+  </note>
+
+  <sect2>
+   <title>Concepts</title>
+
+   <para>
+    Conceptually, every datum of a collatable data type has a
+    collation.  (Collatable data types in the base system are
+    <type>text</type>, <type>varchar</type>, and <type>char</type>.
+    User-defined base types can also be marked collatable.)  If the
+    datum is a column reference, the collation of the datum is the
+    defined collation of the column.  If the datum is a constant, the
+    collation is the default collation of the data type of the
+    constant.  The collation of more complex expressions is derived
+    from the input collations as described below.
+   </para>
+
+   <para>
+    The collation of a datum can also be the <quote>default</quote>
+    collation, which reverts to the locale settings defined for the
+    database.  In some cases, a datum can also have no known
+    collation.  In such cases, ordering operations and other
+    operations that need to know the collation will fail.
+   </para>
+
+   <para>
+    When the database system has to perform an ordering or a
+    comparison, it considers the collation of the input data.  This
+    happens in two situations: an <literal>ORDER BY</literal> clause
+    and a function or operator call such as <literal>&lt;</literal>.
+    The collation to apply for the performance of the <literal>ORDER
+    BY</literal> clause is simply the collation of the sort key.  The
+    collation to apply for a function or operator call is derived from
+    the arguments, as described below.  Additionally, collations are
+    taken into account by functions that convert between lower and
+    upper case letters, that is, <function>lower</function>,
+    <function>upper</function>, and <function>initcap</function>.
+   </para>
+
+   <para>
+    For a function call, the collation that is derived from combining
+    the argument collations is both used for performing any
+    comparisons or ordering and for the collation of the function
+    result, if the result type is collatable.
+   </para>
+
+   <para>
+    The <firstterm>collation derivation</firstterm> of a datum can be
+    implicit or explicit.  This distinction affects how collations are
+    combined when multiple different collations appear in an
+    expression.  An explicit collation derivation arises when a
+    <literal>COLLATE</literal> clause is used; all other collation
+    derivations are implicit.  When multiple collations need to be
+    combined, for example in a function call, the following rules are
+    used:
+
+    <orderedlist>
+     <listitem>
+      <para>
+       If any input item has an explicit collation derivation, then
+       all explicitly derived collations among the input items must be
+       the same, otherwise an error is raised.  If an explicitly
+       derived collation is present, that is the result of the
+       collation combination.
+      </para>
+     </listitem>
+
+     <listitem>
+      <para>
+       Otherwise, all input items must have the same implicit
+       collation derivation or the default collation.  If an
+       implicitly derived collation is present, that is the result of
+       the collation combination.  Otherwise, the result is the
+       default collation.
+      </para>
+     </listitem>
+    </orderedlist>
+
+    For example, take this table definition:
+<programlisting>
+CREATE TABLE test1 (
+    a text COLLATE "x",
+    ...
+);
+</programlisting>
+
+    Then in
+<programlisting>
+SELECT a || 'foo' FROM test1;
+</programlisting>
+    the result collation of the <literal>||</literal> operator is
+    <literal>"x"</literal> because it combines an implicitly derived
+    collation with the default collation.  But in
+<programlisting>
+SELECT a || ('foo' COLLATE "y") FROM test1;
+</programlisting>
+    the result collation is <literal>"y"</literal> because the explicit
+    collation derivation overrides the implicit one.
+   </para>
+  </sect2>
+
+  <sect2>
+   <title>Managing Collations</title>
+
+   <para>
+    A collation is an SQL schema object that maps an SQL name to
+    operating system locales.  In particular, it maps to a combination
+    of <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>.  (As
+    the name would indicate, the main purpose of a collation is to set
+    <symbol>LC_COLLATE</symbol>, which controls the sort order.  But
+    it is rarely necessary in practice to have an
+    <symbol>LC_CTYPE</symbol> setting that is different from
+    <symbol>LC_COLLATE</symbol>, so it is more convenient to collect
+    these under one concept than to create another infrastructure for
+    setting <symbol>LC_CTYPE</symbol> per datum.)  Also, a collation
+    is tied to a character encoding.  The same collation name may
+    exist for different encodings.
+   </para>
+
+   <para>
+    When a database system is initialized, <command>initdb</command>
+    populates the system catalog <literal>pg_collation</literal> with
+    collations based on all the locales it finds on the operating
+    system at the time.  For example, the operating system might
+    provide a locale named <literal>de_DE.utf8</literal>.
+    <command>initdb</command> would then create a collation named
+    <literal>de_DE.utf8</literal> for encoding <literal>UTF8</literal>
+    that has both <symbol>LC_COLLATE</symbol> and
+    <symbol>LC_CTYPE</symbol> set to <literal>de_DE.utf8</literal>.
+    It will also create a collation with the <literal>.utf8</literal>
+    tag stripped off the name.  So you could also use the collation
+    under the name <literal>de_DE</literal>, which is less cumbersome
+    to write and makes the name less encoding-dependent.  Note that,
+    nevertheless, the initial set of collation names is
+    platform-dependent.
+   </para>
+
+   <para>
+    In case a collation is needed that has different values for
+    <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>, or a
+    different name is needed for a collation (for example, for
+    compatibility with existing applications), a new collation may be
+    created.  But there is currently no SQL-level support for creating
+    or changing collations.
+   </para>
+  </sect2>
+ </sect1>
+
  <sect1 id="multibyte">
   <title>Character Set Support</title>
 

doc/src/sgml/func.sgml

@@ -13059,6 +13059,12 @@ SELECT relname FROM pg_class WHERE pg_table_is_visible(oid);
      </thead>
 
      <tbody>
+      <row>
+       <entry><literal><function>pg_collation_is_visible(<parameter>collation_oid</parameter>)</function></literal>
+       </entry>
+       <entry><type>boolean</type></entry>
+       <entry>is collation visible in search path</entry>
+      </row>
       <row>
        <entry><literal><function>pg_conversion_is_visible(<parameter>conversion_oid</parameter>)</function></literal>
        </entry>
@@ -13123,6 +13129,9 @@ SELECT relname FROM pg_class WHERE pg_table_is_visible(oid);
     </tgroup>
    </table>
 
+   <indexterm>
+    <primary>pg_collation_is_visible</primary>
+   </indexterm>
    <indexterm>
     <primary>pg_conversion_is_visible</primary>
    </indexterm>
@@ -13256,7 +13265,7 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
 
      <tbody>
       <row>
-       <entry><literal><function>format_type(<parameter>type_oid</parameter>, <parameter>typemod</>)</function></literal></entry>
+       <entry><literal><function>format_type(<parameter>type_oid</parameter> [, <parameter>typemod</> [, <parameter>collation_oid</> ]])</function></literal></entry>
        <entry><type>text</type></entry>
        <entry>get SQL name of a data type</entry>
       </row>
@@ -13392,7 +13401,9 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
   <para>
    <function>format_type</function> returns the SQL name of a data type that
    is identified by its type OID and possibly a type modifier.  Pass NULL
-   for the type modifier if no specific modifier is known.
+   for the type modifier or omit the argument if no specific modifier is known.
+   If a collation is given as third argument, a <literal>COLLATE</> clause
+   followed by a formatted collation name is appended.
   </para>
 
   <para>

doc/src/sgml/indices.sgml

@@ -921,6 +921,7 @@ CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable>
    defining two operator classes for the data type and then selecting
    the proper class when making an index.  The operator class determines
    the basic sort ordering (which can then be modified by adding sort options
+   <literal>COLLATE</literal>,
    <literal>ASC</>/<literal>DESC</> and/or
    <literal>NULLS FIRST</>/<literal>NULLS LAST</>).
   </para>
@@ -1002,6 +1003,47 @@ SELECT am.amname AS index_method,
  </sect1>
 
 
+ <sect1 id="indexes-collations">
+  <title>Collations and Indexes</title>
+
+  <para>
+   An index can only support one collation for one column or
+   expression.  If multiple collations are of interest, multiple
+   indexes may be created.
+  </para>
+
+  <para>
+   Consider these statements:
+<programlisting>
+CREATE TABLE test1c (
+    id integer,
+    content varchar COLLATE "x"
+);
+
+CREATE INDEX test1c_content_index ON test1c (content);
+</programlisting>
+   The created index automatically follows the collation of the
+   underlying column, and so a query of the form
+<programlisting>
+SELECT * FROM test1c WHERE content = <replaceable>constant</replaceable>;
+</programlisting>
+   could use the index.
+  </para>
+
+  <para>
+   If in addition, a query of the form, say,
+<programlisting>
+SELECT * FROM test1c WHERE content &gt; <replaceable>constant</replaceable> COLLATE "y";
+</programlisting>
+   is of interest, an additional index could be created that supports
+   the <literal>"y"</literal> collation, like so:
+<programlisting>
+CREATE INDEX test1c_content_index ON test1c (content COLLATE "y");
+</programlisting>
+  </para>
+ </sect1>
+
+
  <sect1 id="indexes-examine">
   <title>Examining Index Usage</title>
 

doc/src/sgml/ref/create_domain.sgml

@@ -22,6 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE DOMAIN <replaceable class="parameter">name</replaceable> [ AS ] <replaceable class="parameter">data_type</replaceable>
+    [ COLLATE <replaceable>collation</replaceable> ]
     [ DEFAULT <replaceable>expression</replaceable> ]
     [ <replaceable class="PARAMETER">constraint</replaceable> [ ... ] ]
 
@@ -83,6 +84,17 @@ CREATE DOMAIN <replaceable class="parameter">name</replaceable> [ AS ] <replacea
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><replaceable>collation</replaceable></term>
+      <listitem>
+       <para>
+        An optional collation for the domain.  If no collation is
+        specified, the database default collation is used (which can
+        be overridden when the domain is used to define a column).
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><literal>DEFAULT <replaceable>expression</replaceable></literal></term>
 

doc/src/sgml/ref/create_index.sgml

@@ -22,7 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ <replaceable class="parameter">name</replaceable> ] ON <replaceable class="parameter">table</replaceable> [ USING <replaceable class="parameter">method</replaceable> ]
-    ( { <replaceable class="parameter">column</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ <replaceable class="parameter">opclass</replaceable> ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] )
+    ( { <replaceable class="parameter">column</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] )
     [ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace</replaceable> ]
     [ WHERE <replaceable class="parameter">predicate</replaceable> ]
@@ -181,6 +181,20 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ <replaceable class="parameter">name</
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><replaceable class="parameter">collation</replaceable></term>
+      <listitem>
+       <para>
+        The name of the collation to use for the index.  By default,
+        the index uses the collation declared for the column to be
+        indexed or the result collation of the expression to be
+        indexed.  Indexes with nondefault collations are
+        available for use by queries that involve expressions using
+        nondefault collations.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><replaceable class="parameter">opclass</replaceable></term>
       <listitem>

doc/src/sgml/ref/create_table.sgml

@@ -22,7 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
-  { <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
+  { <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable>collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
     | <replaceable>table_constraint</replaceable>
     | LIKE <replaceable>parent_table</replaceable> [ <replaceable>like_option</replaceable> ... ] }
     [, ... ]
@@ -244,6 +244,17 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>COLLATE <replaceable>collation</replaceable></literal></term>
+    <listitem>
+     <para>
+      The <literal>COLLATE</> clause assigns a nondefault collation to
+      the column.  By default, the locale settings of the database are
+      used.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>INHERITS ( <replaceable>parent_table</replaceable> [, ... ] )</literal></term>
     <listitem>

doc/src/sgml/ref/create_type.sgml

@@ -45,6 +45,7 @@ CREATE TYPE <replaceable class="parameter">name</replaceable> (
     [ , DEFAULT = <replaceable class="parameter">default</replaceable> ]
     [ , ELEMENT = <replaceable class="parameter">element</replaceable> ]
     [ , DELIMITER = <replaceable class="parameter">delimiter</replaceable> ]
+    [ , COLLATABLE = <replaceable class="parameter">collatable</replaceable> ]
 )
 
 CREATE TYPE <replaceable class="parameter">name</replaceable>
@@ -352,6 +353,16 @@ CREATE TYPE <replaceable class="parameter">name</replaceable>
    with the array element type, not the array type itself.
   </para>
 
+  <para>
+   If the optional
+   parameter <replaceable class="parameter">collatable</replaceable>
+   is true, column definitions and expressions of the type may carry
+   collation information and allow the use of
+   the <literal>COLLATE</literal> clause.  It is up to the
+   implementations of the functions operating on the type to actually
+   make use of the collation information; this does not happen
+   automatically merely by marking the type collatable.
+  </para>
   </refsect2>
 
   <refsect2>

doc/src/sgml/regress.sgml

@@ -236,6 +236,27 @@ gmake check LANG=C MULTIBYTE=EUC_JP
     existing installation.
    </para>
   </sect2>
+
+  <sect2>
+   <title>Extra tests</title>
+
+   <para>
+    The regression test suite contains a few test files that are not
+    run by default, because they might be platform-dependent or take a
+    very long time to run.  You can run these or other extra test
+    files by setting the variable <envar>EXTRA_TESTS</envar>.  For
+    example, to run the <literal>numeric_big</literal> test:
+<screen>
+gmake check EXTRA_TESTS=numeric_big
+</screen>
+    To run the collation tests:
+<screen>
+gmake check EXTRA_TESTS=collate.linux.utf8 LANG=en_US.utf8
+</screen>
+    This test works only on Linux/glibc platforms and when run in a
+    UTF-8 locale.
+   </para>
+  </sect2>
   </sect1>
 
   <sect1 id="regress-evaluation">

doc/src/sgml/syntax.sgml

@@ -1899,6 +1899,54 @@ CAST ( <replaceable>expression</replaceable> AS <replaceable>type</replaceable>
    </note>
   </sect2>
 
+  <sect2 id="sql-syntax-collate-clause">
+   <title>COLLATE Clause</title>
+
+   <indexterm>
+    <primary>COLLATE</primary>
+   </indexterm>
+
+   <para>
+    The <literal>COLLATE</literal> clause overrides the collation of
+    an expression.  It is appended to the expression it applies to:
+<synopsis>
+<replaceable>expr</replaceable> COLLATE <replaceable>collation</replaceable>
+</synopsis>
+    where <replaceable>collation</replaceable> is a possibly
+    schema-qualified identifier.  The <literal>COLLATE</literal>
+    clause binds tighter than operators; parentheses can be used when
+    necessary.
+   </para>
+
+   <para>
+    If no collation is explicitly specified, the database system
+    either derives a collation from the columns involved in the
+    expression, or it defaults to the default collation of the
+    database if no column is involved in the expression.
+   </para>
+
+   <para>
+    The two typical uses of the <literal>COLLATE</literal> clause are
+    overriding the sort order in an <literal>ORDER BY</> clause, for
+    example:
+<programlisting>
+SELECT a, b, c FROM tbl WHERE ... ORDER BY a COLLATE "C";
+</programlisting>
+    and overriding the collation of a function or operator call that
+    has locale-sensitive results, for example:
+<programlisting>
+SELECT * FROM tbl WHERE a > 'foo' COLLATE "C";
+</programlisting>
+    In the latter case it doesn't matter which argument of the
+    operator of function call the <literal>COLLATE</> clause is
+    attached to, because the collation that is applied by the operator
+    or function is derived from all arguments, and
+    the <literal>COLLATE</> clause will override the collations of all
+    other arguments.  Attaching nonmatching <literal>COLLATE</>
+    clauses to more than one argument, however, is an error.
+   </para>
+  </sect2>
+
   <sect2 id="sql-syntax-scalar-subqueries">
    <title>Scalar Subqueries</title>
 

src/backend/access/common/scankey.c

@@ -103,3 +103,16 @@ ScanKeyEntryInitializeWithInfo(ScanKey entry,
 	entry->sk_argument = argument;
 	fmgr_info_copy(&entry->sk_func, finfo, CurrentMemoryContext);
 }
+
+/*
+ * ScanKeyEntryInitializeCollation
+ *
+ * Initialize the collation of a scan key.  This is just a notational
+ * convenience and small abstraction.
+ */
+void
+ScanKeyEntryInitializeCollation(ScanKey entry,
+								Oid collation)
+{
+	entry->sk_func.fn_collation = collation;
+}

src/backend/access/common/tupdesc.c

@@ -488,10 +488,32 @@ TupleDescInitEntry(TupleDesc desc,
 	att->attbyval = typeForm->typbyval;
 	att->attalign = typeForm->typalign;
 	att->attstorage = typeForm->typstorage;
+	att->attcollation = typeForm->typcollation;
 
 	ReleaseSysCache(tuple);
 }
 
+/*
+ * TupleDescInitEntryCollation
+ *
+ * Fill in the collation for an attribute in a previously initialized
+ * tuple descriptor.
+ */
+void
+TupleDescInitEntryCollation(TupleDesc desc,
+							AttrNumber attributeNumber,
+							Oid collationid)
+{
+	/*
+	 * sanity checks
+	 */
+	AssertArg(PointerIsValid(desc));
+	AssertArg(attributeNumber >= 1);
+	AssertArg(attributeNumber <= desc->natts);
+
+	desc->attrs[attributeNumber - 1]->attcollation = collationid;
+}
+
 
 /*
  * BuildDescForRelation
@@ -513,6 +535,7 @@ BuildDescForRelation(List *schema)
 	char	   *attname;
 	Oid			atttypid;
 	int32		atttypmod;
+	Oid			attcollation;
 	int			attdim;
 
 	/*
@@ -536,7 +559,7 @@ BuildDescForRelation(List *schema)
 		attnum++;
 
 		attname = entry->colname;
-		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
+		typenameTypeIdModColl(NULL, entry->typeName, &atttypid, &atttypmod, &attcollation);
 		attdim = list_length(entry->typeName->arrayBounds);
 
 		if (entry->typeName->setof)
@@ -547,6 +570,7 @@ BuildDescForRelation(List *schema)
 
 		TupleDescInitEntry(desc, attnum, attname,
 						   atttypid, atttypmod, attdim);
+		TupleDescInitEntryCollation(desc, attnum, attcollation);
 
 		/* Override TupleDescInitEntry's settings as requested */
 		if (entry->storage)
@@ -588,18 +612,20 @@ BuildDescForRelation(List *schema)
  * with functions returning RECORD.
  */
 TupleDesc
-BuildDescFromLists(List *names, List *types, List *typmods)
+BuildDescFromLists(List *names, List *types, List *typmods, List *collations)
 {
 	int			natts;
 	AttrNumber	attnum;
 	ListCell   *l1;
 	ListCell   *l2;
 	ListCell   *l3;
+	ListCell   *l4;
 	TupleDesc	desc;
 
 	natts = list_length(names);
 	Assert(natts == list_length(types));
 	Assert(natts == list_length(typmods));
+	Assert(natts == list_length(collations));
 
 	/*
 	 * allocate a new tuple descriptor
@@ -610,20 +636,25 @@ BuildDescFromLists(List *names, List *types, List *typmods)
 
 	l2 = list_head(types);
 	l3 = list_head(typmods);
+	l4 = list_head(collations);
 	foreach(l1, names)
 	{
 		char	   *attname = strVal(lfirst(l1));
 		Oid			atttypid;
 		int32		atttypmod;
+		Oid			attcollation;
 
 		atttypid = lfirst_oid(l2);
 		l2 = lnext(l2);
 		atttypmod = lfirst_int(l3);
 		l3 = lnext(l3);
+		attcollation = lfirst_oid(l4);
+		l4 = lnext(l4);
 
 		attnum++;
 
 		TupleDescInitEntry(desc, attnum, attname, atttypid, atttypmod, 0);
+		TupleDescInitEntryCollation(desc, attnum, attcollation);
 	}
 
 	return desc;

src/backend/access/gin/ginutil.c

@@ -22,6 +22,7 @@
 #include "storage/freespace.h"
 #include "storage/indexfsm.h"
 #include "storage/lmgr.h"
+#include "utils/lsyscache.h"
 
 
 /*
@@ -60,6 +61,8 @@ initGinState(GinState *state, Relation index)
 		fmgr_info_copy(&(state->compareFn[i]),
 					   index_getprocinfo(index, i + 1, GIN_COMPARE_PROC),
 					   CurrentMemoryContext);
+		fmgr_info_collation(get_typcollation(index->rd_att->attrs[i]->atttypid),
+							&(state->compareFn[i]));
 		fmgr_info_copy(&(state->extractValueFn[i]),
 					   index_getprocinfo(index, i + 1, GIN_EXTRACTVALUE_PROC),
 					   CurrentMemoryContext);

src/backend/access/index/indexam.c

@@ -872,6 +872,8 @@ index_getprocinfo(Relation irel,
 				 procnum, attnum, RelationGetRelationName(irel));
 
 		fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
+		fmgr_info_collation(irel->rd_index->indcollation.values[attnum-1],
+							locinfo);
 	}
 
 	return locinfo;

src/backend/access/nbtree/nbtsearch.c

@@ -723,6 +723,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
 											   cur->sk_subtype,
 											   procinfo,
 											   cur->sk_argument);
+				ScanKeyEntryInitializeCollation(scankeys + i,
+												cur->sk_func.fn_collation);
 			}
 			else
 			{
@@ -743,6 +745,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
 									   cur->sk_subtype,
 									   cmp_proc,
 									   cur->sk_argument);
+				ScanKeyEntryInitializeCollation(scankeys + i,
+												cur->sk_func.fn_collation);
 			}
 		}
 	}

src/backend/bootstrap/bootstrap.c

@@ -26,6 +26,7 @@
 #include "access/xact.h"
 #include "bootstrap/bootstrap.h"
 #include "catalog/index.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
@@ -88,56 +89,57 @@ struct typinfo
 	bool		byval;
 	char		align;
 	char		storage;
+	Oid			collation;
 	Oid			inproc;
 	Oid			outproc;
 };
 
 static const struct typinfo TypInfo[] = {
-	{"bool", BOOLOID, 0, 1, true, 'c', 'p',
+	{"bool", BOOLOID, 0, 1, true, 'c', 'p', InvalidOid,
 	F_BOOLIN, F_BOOLOUT},
-	{"bytea", BYTEAOID, 0, -1, false, 'i', 'x',
+	{"bytea", BYTEAOID, 0, -1, false, 'i', 'x', InvalidOid,
 	F_BYTEAIN, F_BYTEAOUT},
-	{"char", CHAROID, 0, 1, true, 'c', 'p',
+	{"char", CHAROID, 0, 1, true, 'c', 'p', InvalidOid,
 	F_CHARIN, F_CHAROUT},
-	{"int2", INT2OID, 0, 2, true, 's', 'p',
+	{"int2", INT2OID, 0, 2, true, 's', 'p', InvalidOid,
 	F_INT2IN, F_INT2OUT},
-	{"int4", INT4OID, 0, 4, true, 'i', 'p',
+	{"int4", INT4OID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_INT4IN, F_INT4OUT},
-	{"float4", FLOAT4OID, 0, 4, FLOAT4PASSBYVAL, 'i', 'p',
+	{"float4", FLOAT4OID, 0, 4, FLOAT4PASSBYVAL, 'i', 'p', InvalidOid,
 	F_FLOAT4IN, F_FLOAT4OUT},
-	{"name", NAMEOID, CHAROID, NAMEDATALEN, false, 'c', 'p',
+	{"name", NAMEOID, CHAROID, NAMEDATALEN, false, 'c', 'p', InvalidOid,
 	F_NAMEIN, F_NAMEOUT},
-	{"regclass", REGCLASSOID, 0, 4, true, 'i', 'p',
+	{"regclass", REGCLASSOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_REGCLASSIN, F_REGCLASSOUT},
-	{"regproc", REGPROCOID, 0, 4, true, 'i', 'p',
+	{"regproc", REGPROCOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_REGPROCIN, F_REGPROCOUT},
-	{"regtype", REGTYPEOID, 0, 4, true, 'i', 'p',
+	{"regtype", REGTYPEOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_REGTYPEIN, F_REGTYPEOUT},
-	{"text", TEXTOID, 0, -1, false, 'i', 'x',
+	{"text", TEXTOID, 0, -1, false, 'i', 'x', DEFAULT_COLLATION_OID,
 	F_TEXTIN, F_TEXTOUT},
-	{"oid", OIDOID, 0, 4, true, 'i', 'p',
+	{"oid", OIDOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_OIDIN, F_OIDOUT},
-	{"tid", TIDOID, 0, 6, false, 's', 'p',
+	{"tid", TIDOID, 0, 6, false, 's', 'p', InvalidOid,
 	F_TIDIN, F_TIDOUT},
-	{"xid", XIDOID, 0, 4, true, 'i', 'p',
+	{"xid", XIDOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_XIDIN, F_XIDOUT},
-	{"cid", CIDOID, 0, 4, true, 'i', 'p',
+	{"cid", CIDOID, 0, 4, true, 'i', 'p', InvalidOid,
 	F_CIDIN, F_CIDOUT},
-	{"pg_node_tree", PGNODETREEOID, 0, -1, false, 'i', 'x',
+	{"pg_node_tree", PGNODETREEOID, 0, -1, false, 'i', 'x', DEFAULT_COLLATION_OID,
 	F_PG_NODE_TREE_IN, F_PG_NODE_TREE_OUT},
-	{"int2vector", INT2VECTOROID, INT2OID, -1, false, 'i', 'p',
+	{"int2vector", INT2VECTOROID, INT2OID, -1, false, 'i', 'p', InvalidOid,
 	F_INT2VECTORIN, F_INT2VECTOROUT},
-	{"oidvector", OIDVECTOROID, OIDOID, -1, false, 'i', 'p',
+	{"oidvector", OIDVECTOROID, OIDOID, -1, false, 'i', 'p', InvalidOid,
 	F_OIDVECTORIN, F_OIDVECTOROUT},
-	{"_int4", INT4ARRAYOID, INT4OID, -1, false, 'i', 'x',
+	{"_int4", INT4ARRAYOID, INT4OID, -1, false, 'i', 'x', InvalidOid,
 	F_ARRAY_IN, F_ARRAY_OUT},
-	{"_text", 1009, TEXTOID, -1, false, 'i', 'x',
+	{"_text", 1009, TEXTOID, -1, false, 'i', 'x', DEFAULT_COLLATION_OID,
 	F_ARRAY_IN, F_ARRAY_OUT},
-	{"_oid", 1028, OIDOID, -1, false, 'i', 'x',
+	{"_oid", 1028, OIDOID, -1, false, 'i', 'x', InvalidOid,
 	F_ARRAY_IN, F_ARRAY_OUT},
-	{"_char", 1002, CHAROID, -1, false, 'i', 'x',
+	{"_char", 1002, CHAROID, -1, false, 'i', 'x', InvalidOid,
 	F_ARRAY_IN, F_ARRAY_OUT},
-	{"_aclitem", 1034, ACLITEMOID, -1, false, 'i', 'x',
+	{"_aclitem", 1034, ACLITEMOID, -1, false, 'i', 'x', InvalidOid,
 	F_ARRAY_IN, F_ARRAY_OUT}
 };
 
@@ -710,6 +712,7 @@ DefineAttr(char *name, char *type, int attnum)
 		attrtypes[attnum]->attbyval = Ap->am_typ.typbyval;
 		attrtypes[attnum]->attstorage = Ap->am_typ.typstorage;
 		attrtypes[attnum]->attalign = Ap->am_typ.typalign;
+		attrtypes[attnum]->attcollation = Ap->am_typ.typcollation;
 		/* if an array type, assume 1-dimensional attribute */
 		if (Ap->am_typ.typelem != InvalidOid && Ap->am_typ.typlen < 0)
 			attrtypes[attnum]->attndims = 1;
@@ -723,6 +726,7 @@ DefineAttr(char *name, char *type, int attnum)
 		attrtypes[attnum]->attbyval = TypInfo[typeoid].byval;
 		attrtypes[attnum]->attstorage = TypInfo[typeoid].storage;
 		attrtypes[attnum]->attalign = TypInfo[typeoid].align;
+		attrtypes[attnum]->attcollation = TypInfo[typeoid].collation;
 		/* if an array type, assume 1-dimensional attribute */
 		if (TypInfo[typeoid].elem != InvalidOid &&
 			attrtypes[attnum]->attlen < 0)

src/backend/catalog/Makefile

@@ -39,7 +39,7 @@ POSTGRES_BKI_SRCS = $(addprefix $(top_srcdir)/src/include/catalog/,\
 	pg_ts_parser.h pg_ts_template.h \
 	pg_foreign_data_wrapper.h pg_foreign_server.h pg_user_mapping.h \
 	pg_foreign_table.h \
-	pg_default_acl.h pg_seclabel.h \
+	pg_default_acl.h pg_seclabel.h pg_collation.h \
 	toasting.h indexing.h \
     )
 

src/backend/catalog/genbki.pl

@@ -340,6 +340,7 @@ sub emit_pgattr_row
             $row{attalign}    = $type->{typalign};
             # set attndims if it's an array type
             $row{attndims}    = $type->{typcategory} eq 'A' ? '1' : '0';
+            $row{attcollation} = $type->{typcollation};
             # attnotnull must be set true if the type is fixed-width and
             # prior columns are too --- compare DefineAttr in bootstrap.c.
             # oidvector and int2vector are also treated as not-nullable.

src/backend/catalog/heap.c

@@ -542,6 +542,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
 	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
 	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
+	values[Anum_pg_attribute_attcollation - 1] = ObjectIdGetDatum(new_attribute->attcollation);
 
 	/* start out with empty permissions and empty options */
 	nulls[Anum_pg_attribute_attacl - 1] = true;
@@ -859,7 +860,8 @@ AddNewRelationType(const char *typeName,
 				   'x',			/* fully TOASTable */
 				   -1,			/* typmod */
 				   0,			/* array dimensions for typBaseType */
-				   false);		/* Type NOT NULL */
+				   false,		/* Type NOT NULL */
+				   InvalidOid);	/* typcollation */
 }
 
 /* --------------------------------
@@ -1120,7 +1122,8 @@ heap_create_with_catalog(const char *relname,
 				   'x',			/* fully TOASTable */
 				   -1,			/* typmod */
 				   0,			/* array dimensions for typBaseType */
-				   false);		/* Type NOT NULL */
+				   false,		/* Type NOT NULL */
+				   InvalidOid);	/* typcollation */
 
 		pfree(relarrayname);
 	}

src/backend/catalog/index.c

@@ -87,12 +87,14 @@ static TupleDesc ConstructTupleDescriptor(Relation heapRelation,
 						 IndexInfo *indexInfo,
 						 List *indexColNames,
 						 Oid accessMethodObjectId,
+						 Oid *collationObjectId,
 						 Oid *classObjectId);
 static void InitializeAttributeOids(Relation indexRelation,
 						int numatts, Oid indexoid);
 static void AppendAttributeTuples(Relation indexRelation, int numatts);
 static void UpdateIndexRelation(Oid indexoid, Oid heapoid,
 					IndexInfo *indexInfo,
+					Oid *collationOids,
 					Oid *classOids,
 					int16 *coloptions,
 					bool primary,
@@ -264,6 +266,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 						 IndexInfo *indexInfo,
 						 List *indexColNames,
 						 Oid accessMethodObjectId,
+						 Oid *collationObjectId,
 						 Oid *classObjectId)
 {
 	int			numatts = indexInfo->ii_NumIndexAttrs;
@@ -398,6 +401,8 @@ ConstructTupleDescriptor(Relation heapRelation,
 			CheckAttributeType(NameStr(to->attname), to->atttypid, false);
 		}
 
+		to->attcollation = collationObjectId[i];
+
 		/*
 		 * We do not yet have the correct relation OID for the index, so just
 		 * set it invalid for now.	InitializeAttributeOids() will fix it
@@ -521,6 +526,7 @@ static void
 UpdateIndexRelation(Oid indexoid,
 					Oid heapoid,
 					IndexInfo *indexInfo,
+					Oid *collationOids,
 					Oid *classOids,
 					int16 *coloptions,
 					bool primary,
@@ -529,6 +535,7 @@ UpdateIndexRelation(Oid indexoid,
 					bool isvalid)
 {
 	int2vector *indkey;
+	oidvector  *indcollation;
 	oidvector  *indclass;
 	int2vector *indoption;
 	Datum		exprsDatum;
@@ -546,6 +553,7 @@ UpdateIndexRelation(Oid indexoid,
 	indkey = buildint2vector(NULL, indexInfo->ii_NumIndexAttrs);
 	for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
 		indkey->values[i] = indexInfo->ii_KeyAttrNumbers[i];
+	indcollation = buildoidvector(collationOids, indexInfo->ii_NumIndexAttrs);
 	indclass = buildoidvector(classOids, indexInfo->ii_NumIndexAttrs);
 	indoption = buildint2vector(coloptions, indexInfo->ii_NumIndexAttrs);
 
@@ -601,6 +609,7 @@ UpdateIndexRelation(Oid indexoid,
 	/* we set isvalid and isready the same way */
 	values[Anum_pg_index_indisready - 1] = BoolGetDatum(isvalid);
 	values[Anum_pg_index_indkey - 1] = PointerGetDatum(indkey);
+	values[Anum_pg_index_indcollation - 1] = PointerGetDatum(indcollation);
 	values[Anum_pg_index_indclass - 1] = PointerGetDatum(indclass);
 	values[Anum_pg_index_indoption - 1] = PointerGetDatum(indoption);
 	values[Anum_pg_index_indexprs - 1] = exprsDatum;
@@ -664,6 +673,7 @@ index_create(Relation heapRelation,
 			 List *indexColNames,
 			 Oid accessMethodObjectId,
 			 Oid tableSpaceId,
+			 Oid *collationObjectId,
 			 Oid *classObjectId,
 			 int16 *coloptions,
 			 Datum reloptions,
@@ -761,6 +771,7 @@ index_create(Relation heapRelation,
 											indexInfo,
 											indexColNames,
 											accessMethodObjectId,
+											collationObjectId,
 											classObjectId);
 
 	/*
@@ -856,7 +867,7 @@ index_create(Relation heapRelation,
 	 * ----------------
 	 */
 	UpdateIndexRelation(indexRelationId, heapRelationId, indexInfo,
-						classObjectId, coloptions, isprimary, is_exclusion,
+						collationObjectId, classObjectId, coloptions, isprimary, is_exclusion,
 						!deferrable,
 						!concurrent);
 
@@ -2370,7 +2381,7 @@ validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
 	ivinfo.strategy = NULL;
 
 	state.tuplesort = tuplesort_begin_datum(TIDOID,
-											TIDLessOperator, false,
+											TIDLessOperator, InvalidOid, false,
 											maintenance_work_mem,
 											false);
 	state.htups = state.itups = state.tups_inserted = 0;

src/backend/catalog/namespace.c

@@ -23,6 +23,7 @@
 #include "catalog/dependency.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_authid.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_conversion.h"
 #include "catalog/pg_conversion_fn.h"
 #include "catalog/pg_namespace.h"
@@ -37,6 +38,7 @@
 #include "catalog/pg_type.h"
 #include "commands/dbcommands.h"
 #include "funcapi.h"
+#include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "parser/parse_func.h"
@@ -198,6 +200,7 @@ Datum		pg_type_is_visible(PG_FUNCTION_ARGS);
 Datum		pg_function_is_visible(PG_FUNCTION_ARGS);
 Datum		pg_operator_is_visible(PG_FUNCTION_ARGS);
 Datum		pg_opclass_is_visible(PG_FUNCTION_ARGS);
+Datum		pg_collation_is_visible(PG_FUNCTION_ARGS);
 Datum		pg_conversion_is_visible(PG_FUNCTION_ARGS);
 Datum		pg_ts_parser_is_visible(PG_FUNCTION_ARGS);
 Datum		pg_ts_dict_is_visible(PG_FUNCTION_ARGS);
@@ -1610,6 +1613,89 @@ OpfamilyIsVisible(Oid opfid)
 	return visible;
 }
 
+/*
+ * CollationGetCollid
+ *		Try to resolve an unqualified collation name.
+ *		Returns OID if collation found in search path, else InvalidOid.
+ *
+ * This is essentially the same as RelnameGetRelid.
+ */
+Oid
+CollationGetCollid(const char *collname)
+{
+	Oid			collid;
+	ListCell   *l;
+
+	recomputeNamespacePath();
+
+	foreach(l, activeSearchPath)
+	{
+		Oid			namespaceId = lfirst_oid(l);
+
+		if (namespaceId == myTempNamespace)
+			continue;			/* do not look in temp namespace */
+
+		collid = GetSysCacheOid3(COLLNAMEENCNSP,
+								 PointerGetDatum(collname),
+								 Int32GetDatum(GetDatabaseEncoding()),
+								 ObjectIdGetDatum(namespaceId));
+		if (OidIsValid(collid))
+			return collid;
+	}
+
+	/* Not found in path */
+	return InvalidOid;
+}
+
+/*
+ * CollationIsVisible
+ *		Determine whether a collation (identified by OID) is visible in the
+ *		current search path.  Visible means "would be found by searching
+ *		for the unqualified collation name".
+ */
+bool
+CollationIsVisible(Oid collid)
+{
+	HeapTuple	colltup;
+	Form_pg_collation collform;
+	Oid			collnamespace;
+	bool		visible;
+
+	colltup = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
+	if (!HeapTupleIsValid(colltup))
+		elog(ERROR, "cache lookup failed for collation %u", collid);
+	collform = (Form_pg_collation) GETSTRUCT(colltup);
+
+	recomputeNamespacePath();
+
+	/*
+	 * Quick check: if it ain't in the path at all, it ain't visible. Items in
+	 * the system namespace are surely in the path and so we needn't even do
+	 * list_member_oid() for them.
+	 */
+	collnamespace = collform->collnamespace;
+	if (collnamespace != PG_CATALOG_NAMESPACE &&
+		!list_member_oid(activeSearchPath, collnamespace))
+		visible = false;
+	else
+	{
+		/*
+		 * If it is in the path, it might still not be visible; it could be
+		 * hidden by another conversion of the same name earlier in the path.
+		 * So we must do a slow check to see if this conversion would be found
+		 * by CollationGetCollid.
+		 */
+		char	   *collname = NameStr(collform->collname);
+
+		visible = (CollationGetCollid(collname) == collid);
+	}
+
+	ReleaseSysCache(colltup);
+
+	return visible;
+}
+
+
 /*
  * ConversionGetConid
  *		Try to resolve an unqualified conversion name.
@@ -2807,6 +2893,63 @@ PopOverrideSearchPath(void)
 }
 
 
+/*
+ * get_collation_oid - find a collation by possibly qualified name
+ */
+Oid
+get_collation_oid(List *name, bool missing_ok)
+{
+	char	   *schemaname;
+	char	   *collation_name;
+	Oid			namespaceId;
+	Oid			colloid = InvalidOid;
+	ListCell   *l;
+	int			encoding;
+
+	encoding = GetDatabaseEncoding();
+
+	/* deconstruct the name list */
+	DeconstructQualifiedName(name, &schemaname, &collation_name);
+
+	if (schemaname)
+	{
+		/* use exact schema given */
+		namespaceId = LookupExplicitNamespace(schemaname);
+		colloid = GetSysCacheOid3(COLLNAMEENCNSP,
+								  PointerGetDatum(collation_name),
+								  Int32GetDatum(encoding),
+								  ObjectIdGetDatum(namespaceId));
+	}
+	else
+	{
+		/* search for it in search path */
+		recomputeNamespacePath();
+
+		foreach(l, activeSearchPath)
+		{
+			namespaceId = lfirst_oid(l);
+
+			if (namespaceId == myTempNamespace)
+				continue;		/* do not look in temp namespace */
+
+			colloid = GetSysCacheOid3(COLLNAMEENCNSP,
+									  PointerGetDatum(collation_name),
+									  Int32GetDatum(encoding),
+									  ObjectIdGetDatum(namespaceId));
+			if (OidIsValid(colloid))
+				return colloid;
+		}
+	}
+
+	/* Not found in path */
+	if (!OidIsValid(colloid) && !missing_ok)
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("collation \"%s\" for current database encoding \"%s\" does not exist",
+						NameListToString(name), GetDatabaseEncodingName())));
+	return colloid;
+}
+
 /*
  * get_conversion_oid - find a conversion by possibly qualified name
  */
@@ -3566,6 +3709,17 @@ pg_opclass_is_visible(PG_FUNCTION_ARGS)
 	PG_RETURN_BOOL(OpclassIsVisible(oid));
 }
 
+Datum
+pg_collation_is_visible(PG_FUNCTION_ARGS)
+{
+	Oid			oid = PG_GETARG_OID(0);
+
+	if (!SearchSysCacheExists1(COLLOID, ObjectIdGetDatum(oid)))
+		PG_RETURN_NULL();
+
+	PG_RETURN_BOOL(CollationIsVisible(oid));
+}
+
 Datum
 pg_conversion_is_visible(PG_FUNCTION_ARGS)
 {

src/backend/catalog/pg_type.c

@@ -114,6 +114,7 @@ TypeShellMake(const char *typeName, Oid typeNamespace, Oid ownerId)
 	values[i++] = ObjectIdGetDatum(InvalidOid); /* typbasetype */
 	values[i++] = Int32GetDatum(-1);	/* typtypmod */
 	values[i++] = Int32GetDatum(0);		/* typndims */
+	values[i++] = ObjectIdGetDatum(InvalidOid);	/* typcollation */
 	nulls[i++] = true;			/* typdefaultbin */
 	nulls[i++] = true;			/* typdefault */
 
@@ -210,7 +211,8 @@ TypeCreate(Oid newTypeOid,
 		   char storage,
 		   int32 typeMod,
 		   int32 typNDims,		/* Array dimensions for baseType */
-		   bool typeNotNull)
+		   bool typeNotNull,
+		   Oid typeCollation)
 {
 	Relation	pg_type_desc;
 	Oid			typeObjectId;
@@ -348,6 +350,7 @@ TypeCreate(Oid newTypeOid,
 	values[i++] = ObjectIdGetDatum(baseType);	/* typbasetype */
 	values[i++] = Int32GetDatum(typeMod);		/* typtypmod */
 	values[i++] = Int32GetDatum(typNDims);		/* typndims */
+	values[i++] = ObjectIdGetDatum(typeCollation);	/* typcollation */
 
 	/*
 	 * initialize the default binary value for this type.  Check for nulls of

src/backend/catalog/system_views.sql

@@ -671,6 +671,10 @@ COMMENT ON FUNCTION ts_debug(text) IS
 -- to get filled in.)
 --
 
+CREATE OR REPLACE FUNCTION
+  format_type(oid, int DEFAULT NULL, oid DEFAULT NULL)
+  RETURNS text STABLE LANGUAGE internal AS 'format_type';
+
 CREATE OR REPLACE FUNCTION
   pg_start_backup(label text, fast boolean DEFAULT false)
   RETURNS text STRICT VOLATILE LANGUAGE internal AS 'pg_start_backup';

src/backend/catalog/toasting.c

@@ -124,6 +124,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptio
 	char		toast_relname[NAMEDATALEN];
 	char		toast_idxname[NAMEDATALEN];
 	IndexInfo  *indexInfo;
+	Oid			collationObjectId[2];
 	Oid			classObjectId[2];
 	int16		coloptions[2];
 	ObjectAddress baseobject,
@@ -264,6 +265,9 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptio
 	indexInfo->ii_Concurrent = false;
 	indexInfo->ii_BrokenHotChain = false;
 
+	collationObjectId[0] = InvalidOid;
+	collationObjectId[1] = InvalidOid;
+
 	classObjectId[0] = OID_BTREE_OPS_OID;
 	classObjectId[1] = INT4_BTREE_OPS_OID;
 
@@ -275,7 +279,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, Datum reloptio
 							   list_make2("chunk_id", "chunk_seq"),
 							   BTREE_AM_OID,
 							   rel->rd_rel->reltablespace,
-							   classObjectId, coloptions, (Datum) 0,
+							   collationObjectId, classObjectId, coloptions, (Datum) 0,
 							   true, false, false, false,
 							   true, false, false);
 

src/backend/commands/analyze.c

@@ -862,11 +862,13 @@ examine_attribute(Relation onerel, int attnum, Node *index_expr)
 	{
 		stats->attrtypid = exprType(index_expr);
 		stats->attrtypmod = exprTypmod(index_expr);
+		stats->attrcollation = exprCollation(index_expr);
 	}
 	else
 	{
 		stats->attrtypid = attr->atttypid;
 		stats->attrtypmod = attr->atttypmod;
+		stats->attrcollation = attr->attcollation;
 	}
 
 	typtuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(stats->attrtypid));
@@ -1929,6 +1931,7 @@ compute_minimal_stats(VacAttrStatsP stats,
 	track_cnt = 0;
 
 	fmgr_info(mystats->eqfunc, &f_cmpeq);
+	fmgr_info_collation(stats->attrcollation, &f_cmpeq);
 
 	for (i = 0; i < samplerows; i++)
 	{
@@ -2250,6 +2253,7 @@ compute_scalar_stats(VacAttrStatsP stats,
 
 	SelectSortFunction(mystats->ltopr, false, &cmpFn, &cmpFlags);
 	fmgr_info(cmpFn, &f_cmpfn);
+	fmgr_info_collation(stats->attrcollation, &f_cmpfn);
 
 	/* Initial scan to find sortable values */
 	for (i = 0; i < samplerows; i++)

src/backend/commands/dbcommands.c

@@ -356,8 +356,8 @@ createdb(const CreatedbStmt *stmt)
 	 *
 	 * Note: if you change this policy, fix initdb to match.
 	 */
-	ctype_encoding = pg_get_encoding_from_locale(dbctype);
-	collate_encoding = pg_get_encoding_from_locale(dbcollate);
+	ctype_encoding = pg_get_encoding_from_locale(dbctype, true);
+	collate_encoding = pg_get_encoding_from_locale(dbcollate, true);
 
 	if (!(ctype_encoding == encoding ||
 		  ctype_encoding == PG_SQL_ASCII ||

src/backend/commands/functioncmds.c

@@ -87,7 +87,7 @@ compute_return_type(TypeName *returnType, Oid languageOid,
 	Oid			rettype;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, returnType, NULL);
+	typtup = LookupTypeName(NULL, returnType, NULL, NULL);
 
 	if (typtup)
 	{
@@ -207,7 +207,7 @@ examine_parameter_list(List *parameters, Oid languageOid,
 		Oid			toid;
 		Type		typtup;
 
-		typtup = LookupTypeName(NULL, t, NULL);
+		typtup = LookupTypeName(NULL, t, NULL, NULL);
 		if (typtup)
 		{
 			if (!((Form_pg_type) GETSTRUCT(typtup))->typisdefined)

src/backend/commands/indexcmds.c

@@ -58,6 +58,7 @@
 /* non-export function prototypes */
 static void CheckPredicate(Expr *predicate);
 static void ComputeIndexAttrs(IndexInfo *indexInfo,
+				  Oid *collationOidP,
 				  Oid *classOidP,
 				  int16 *colOptionP,
 				  List *attList,
@@ -124,6 +125,7 @@ DefineIndex(RangeVar *heapRelation,
 			bool quiet,
 			bool concurrent)
 {
+	Oid		   *collationObjectId;
 	Oid		   *classObjectId;
 	Oid			accessMethodId;
 	Oid			relationId;
@@ -345,9 +347,10 @@ DefineIndex(RangeVar *heapRelation,
 	indexInfo->ii_Concurrent = concurrent;
 	indexInfo->ii_BrokenHotChain = false;
 
+	collationObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	classObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	coloptions = (int16 *) palloc(numberOfAttributes * sizeof(int16));
-	ComputeIndexAttrs(indexInfo, classObjectId, coloptions, attributeList,
+	ComputeIndexAttrs(indexInfo, collationObjectId, classObjectId, coloptions, attributeList,
 					  exclusionOpNames, relationId,
 					  accessMethodName, accessMethodId,
 					  amcanorder, isconstraint);
@@ -392,7 +395,7 @@ DefineIndex(RangeVar *heapRelation,
 	indexRelationId =
 		index_create(rel, indexRelationName, indexRelationId,
 					 indexInfo, indexColNames,
-					 accessMethodId, tablespaceId, classObjectId,
+					 accessMethodId, tablespaceId, collationObjectId, classObjectId,
 					 coloptions, reloptions, primary,
 					 isconstraint, deferrable, initdeferred,
 					 allowSystemTableMods,
@@ -764,6 +767,7 @@ CheckPredicate(Expr *predicate)
  */
 static void
 ComputeIndexAttrs(IndexInfo *indexInfo,
+				  Oid *collationOidP,
 				  Oid *classOidP,
 				  int16 *colOptionP,
 				  List *attList,	/* list of IndexElem's */
@@ -800,6 +804,7 @@ ComputeIndexAttrs(IndexInfo *indexInfo,
 	{
 		IndexElem  *attribute = (IndexElem *) lfirst(lc);
 		Oid			atttype;
+		Oid			attcollation;
 
 		/*
 		 * Process the column-or-expression to be indexed.
@@ -829,6 +834,7 @@ ComputeIndexAttrs(IndexInfo *indexInfo,
 			attform = (Form_pg_attribute) GETSTRUCT(atttuple);
 			indexInfo->ii_KeyAttrNumbers[attn] = attform->attnum;
 			atttype = attform->atttypid;
+			attcollation = attform->attcollation;
 			ReleaseSysCache(atttuple);
 		}
 		else if (attribute->expr && IsA(attribute->expr, Var) &&
@@ -839,6 +845,7 @@ ComputeIndexAttrs(IndexInfo *indexInfo,
 
 			indexInfo->ii_KeyAttrNumbers[attn] = var->varattno;
 			atttype = get_atttype(relId, var->varattno);
+			attcollation = var->varcollid;
 		}
 		else
 		{
@@ -848,6 +855,7 @@ ComputeIndexAttrs(IndexInfo *indexInfo,
 			indexInfo->ii_Expressions = lappend(indexInfo->ii_Expressions,
 												attribute->expr);
 			atttype = exprType(attribute->expr);
+			attcollation = exprCollation(attribute->expr);
 
 			/*
 			 * We don't currently support generation of an actual query plan
@@ -874,6 +882,20 @@ ComputeIndexAttrs(IndexInfo *indexInfo,
 						 errmsg("functions in index expression must be marked IMMUTABLE")));
 		}
 
+		/*
+		 * Collation override
+		 */
+		if (attribute->collation)
+		{
+			if (!type_is_collatable(atttype))
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("collations are not supported by type %s",
+								format_type_be(atttype))));
+			attcollation = get_collation_oid(attribute->collation, false);
+		}
+		collationOidP[attn] = attcollation;
+
 		/*
 		 * Identify the opclass to use.
 		 */

src/backend/commands/seclabel.c

@@ -15,6 +15,7 @@
 #include "catalog/catalog.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_seclabel.h"
 #include "commands/seclabel.h"
 #include "miscadmin.h"
@@ -194,6 +195,7 @@ GetSecurityLabel(const ObjectAddress *object, const char *provider)
 				Anum_pg_seclabel_provider,
 				BTEqualStrategyNumber, F_TEXTEQ,
 				CStringGetTextDatum(provider));
+	ScanKeyEntryInitializeCollation(&keys[3], DEFAULT_COLLATION_OID);
 
 	pg_seclabel = heap_open(SecLabelRelationId, AccessShareLock);
 
@@ -263,6 +265,7 @@ SetSecurityLabel(const ObjectAddress *object,
 				Anum_pg_seclabel_provider,
 				BTEqualStrategyNumber, F_TEXTEQ,
 				CStringGetTextDatum(provider));
+	ScanKeyEntryInitializeCollation(&keys[3], DEFAULT_COLLATION_OID);
 
 	pg_seclabel = heap_open(SecLabelRelationId, RowExclusiveLock);
 

src/backend/commands/sequence.c

@@ -143,53 +143,53 @@ DefineSequence(CreateSeqStmt *seq)
 		switch (i)
 		{
 			case SEQ_COL_NAME:
-				coldef->typeName = makeTypeNameFromOid(NAMEOID, -1);
+				coldef->typeName = makeTypeNameFromOid(NAMEOID, -1, InvalidOid);
 				coldef->colname = "sequence_name";
 				namestrcpy(&name, seq->sequence->relname);
 				value[i - 1] = NameGetDatum(&name);
 				break;
 			case SEQ_COL_LASTVAL:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "last_value";
 				value[i - 1] = Int64GetDatumFast(new.last_value);
 				break;
 			case SEQ_COL_STARTVAL:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "start_value";
 				value[i - 1] = Int64GetDatumFast(new.start_value);
 				break;
 			case SEQ_COL_INCBY:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "increment_by";
 				value[i - 1] = Int64GetDatumFast(new.increment_by);
 				break;
 			case SEQ_COL_MAXVALUE:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "max_value";
 				value[i - 1] = Int64GetDatumFast(new.max_value);
 				break;
 			case SEQ_COL_MINVALUE:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "min_value";
 				value[i - 1] = Int64GetDatumFast(new.min_value);
 				break;
 			case SEQ_COL_CACHE:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "cache_value";
 				value[i - 1] = Int64GetDatumFast(new.cache_value);
 				break;
 			case SEQ_COL_LOG:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
 				coldef->colname = "log_cnt";
 				value[i - 1] = Int64GetDatum((int64) 1);
 				break;
 			case SEQ_COL_CYCLE:
-				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1);
+				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1, InvalidOid);
 				coldef->colname = "is_cycled";
 				value[i - 1] = BoolGetDatum(new.is_cycled);
 				break;
 			case SEQ_COL_CALLED:
-				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1);
+				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1, InvalidOid);
 				coldef->colname = "is_called";
 				value[i - 1] = BoolGetDatum(false);
 				break;

src/backend/commands/tablecmds.c

@@ -1422,6 +1422,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			{
 				Oid			defTypeId;
 				int32		deftypmod;
+				Oid			defCollId;
 
 				/*
 				 * Yes, try to merge the two column definitions. They must
@@ -1431,7 +1432,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
 				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
+				typenameTypeIdModColl(NULL, def->typeName, &defTypeId, &deftypmod, &defCollId);
 				if (defTypeId != attribute->atttypid ||
 					deftypmod != attribute->atttypmod)
 					ereport(ERROR,
@@ -1441,6 +1442,14 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 							 errdetail("%s versus %s",
 									   TypeNameToString(def->typeName),
 									   format_type_be(attribute->atttypid))));
+				if (defCollId != attribute->attcollation)
+					ereport(ERROR,
+							(errcode(ERRCODE_COLLATION_MISMATCH),
+							 errmsg("inherited column \"%s\" has a collation conflict",
+									attributeName),
+							 errdetail("\"%s\" versus \"%s\"",
+									   get_collation_name(defCollId),
+									   get_collation_name(attribute->attcollation))));
 
 				/* Copy storage parameter */
 				if (def->storage == 0)
@@ -1468,7 +1477,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				def = makeNode(ColumnDef);
 				def->colname = pstrdup(attributeName);
 				def->typeName = makeTypeNameFromOid(attribute->atttypid,
-													attribute->atttypmod);
+													attribute->atttypmod,
+													attribute->attcollation);
 				def->inhcount = 1;
 				def->is_local = false;
 				def->is_not_null = attribute->attnotnull;
@@ -1594,6 +1604,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 							newTypeId;
 				int32		deftypmod,
 							newtypmod;
+				Oid			defcollid,
+							newcollid;
 
 				/*
 				 * Yes, try to merge the two column definitions. They must
@@ -1603,8 +1615,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				   (errmsg("merging column \"%s\" with inherited definition",
 						   attributeName)));
 				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
+				typenameTypeIdModColl(NULL, def->typeName, &defTypeId, &deftypmod, &defcollid);
+				typenameTypeIdModColl(NULL, newdef->typeName, &newTypeId, &newtypmod, &newcollid);
 				if (defTypeId != newTypeId || deftypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
@@ -1613,6 +1625,14 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 							 errdetail("%s versus %s",
 									   TypeNameToString(def->typeName),
 									   TypeNameToString(newdef->typeName))));
+				if (defcollid != newcollid)
+					ereport(ERROR,
+							(errcode(ERRCODE_COLLATION_MISMATCH),
+							 errmsg("column \"%s\" has a collation conflict",
+									attributeName),
+							 errdetail("\"%s\" versus \"%s\"",
+									   get_collation_name(defcollid),
+									   get_collation_name(newcollid))));
 
 				/* Copy storage parameter */
 				if (def->storage == 0)
@@ -4065,6 +4085,7 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
 	HeapTuple	typeTuple;
 	Oid			typeOid;
 	int32		typmod;
+	Oid			collOid;
 	Form_pg_type tform;
 	Expr	   *defval;
 
@@ -4085,15 +4106,24 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
 			Form_pg_attribute childatt = (Form_pg_attribute) GETSTRUCT(tuple);
 			Oid			ctypeId;
 			int32		ctypmod;
+			Oid			ccollid;
 
 			/* Child column must match by type */
-			typenameTypeIdAndMod(NULL, colDef->typeName, &ctypeId, &ctypmod);
+			typenameTypeIdModColl(NULL, colDef->typeName, &ctypeId, &ctypmod, &ccollid);
 			if (ctypeId != childatt->atttypid ||
 				ctypmod != childatt->atttypmod)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("child table \"%s\" has different type for column \"%s\"",
 							RelationGetRelationName(rel), colDef->colname)));
+			if (ccollid != childatt->attcollation)
+				ereport(ERROR,
+						(errcode(ERRCODE_COLLATION_MISMATCH),
+						 errmsg("child table \"%s\" has different collation for column \"%s\"",
+								RelationGetRelationName(rel), colDef->colname),
+						 errdetail("\"%s\" versus \"%s\"",
+								   get_collation_name(ccollid),
+								   get_collation_name(childatt->attcollation))));
 
 			/* If it's OID, child column must actually be OID */
 			if (isOid && childatt->attnum != ObjectIdAttributeNumber)
@@ -4151,7 +4181,7 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
 							MaxHeapAttributeNumber)));
 	}
 
-	typeTuple = typenameType(NULL, colDef->typeName, &typmod);
+	typeTuple = typenameType(NULL, colDef->typeName, &typmod, &collOid);
 	tform = (Form_pg_type) GETSTRUCT(typeTuple);
 	typeOid = HeapTupleGetOid(typeTuple);
 
@@ -4176,6 +4206,7 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
+	attribute.attcollation = collOid;
 	/* attribute.attacl is handled by InsertPgAttributeTuple */
 
 	ReleaseSysCache(typeTuple);
@@ -4353,7 +4384,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		ColumnDef  *cdef = makeNode(ColumnDef);
 
 		cdef->colname = pstrdup("oid");
-		cdef->typeName = makeTypeNameFromOid(OIDOID, -1);
+		cdef->typeName = makeTypeNameFromOid(OIDOID, -1, InvalidOid);
 		cdef->inhcount = 0;
 		cdef->is_local = true;
 		cdef->is_not_null = true;
@@ -6415,6 +6446,7 @@ ATPrepAlterColumnType(List **wqueue,
 	AttrNumber	attnum;
 	Oid			targettype;
 	int32		targettypmod;
+	Oid			targetcollid;
 	Node	   *transform;
 	NewColumnValue *newval;
 	ParseState *pstate = make_parsestate(NULL);
@@ -6449,7 +6481,7 @@ ATPrepAlterColumnType(List **wqueue,
 						colName)));
 
 	/* Look up the target type */
-	typenameTypeIdAndMod(NULL, typeName, &targettype, &targettypmod);
+	typenameTypeIdModColl(NULL, typeName, &targettype, &targettypmod, &targetcollid);
 
 	/* make sure datatype is legal for a column */
 	CheckAttributeType(colName, targettype, false);
@@ -6501,7 +6533,7 @@ ATPrepAlterColumnType(List **wqueue,
 		else
 		{
 			transform = (Node *) makeVar(1, attnum,
-										 attTup->atttypid, attTup->atttypmod,
+										 attTup->atttypid, attTup->atttypmod, attTup->attcollation,
 										 0);
 		}
 
@@ -6578,6 +6610,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	Form_pg_type tform;
 	Oid			targettype;
 	int32		targettypmod;
+	Oid			targetcollid;
 	Node	   *defaultexpr;
 	Relation	attrelation;
 	Relation	depRel;
@@ -6606,7 +6639,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 						colName)));
 
 	/* Look up the target type (should not fail, since prep found it) */
-	typeTuple = typenameType(NULL, typeName, &targettypmod);
+	typeTuple = typenameType(NULL, typeName, &targettypmod, &targetcollid);
 	tform = (Form_pg_type) GETSTRUCT(typeTuple);
 	targettype = HeapTupleGetOid(typeTuple);
 
@@ -6880,6 +6913,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	 */
 	attTup->atttypid = targettype;
 	attTup->atttypmod = targettypmod;
+	attTup->attcollation = targetcollid;
 	attTup->attndims = list_length(typeName->arrayBounds);
 	attTup->attlen = tform->typlen;
 	attTup->attbyval = tform->typbyval;

src/backend/commands/typecmds.c

@@ -38,6 +38,7 @@
 #include "catalog/dependency.h"
 #include "catalog/heap.h"
 #include "catalog/indexing.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_enum.h"
@@ -118,6 +119,7 @@ DefineType(List *names, List *parameters)
 	bool		byValue = false;
 	char		alignment = 'i';	/* default alignment */
 	char		storage = 'p';	/* default TOAST storage method */
+	Oid			collation = InvalidOid;
 	DefElem    *likeTypeEl = NULL;
 	DefElem    *internalLengthEl = NULL;
 	DefElem    *inputNameEl = NULL;
@@ -135,6 +137,7 @@ DefineType(List *names, List *parameters)
 	DefElem    *byValueEl = NULL;
 	DefElem    *alignmentEl = NULL;
 	DefElem    *storageEl = NULL;
+	DefElem	   *collatableEl = NULL;
 	Oid			inputOid;
 	Oid			outputOid;
 	Oid			receiveOid = InvalidOid;
@@ -261,6 +264,8 @@ DefineType(List *names, List *parameters)
 			defelp = &alignmentEl;
 		else if (pg_strcasecmp(defel->defname, "storage") == 0)
 			defelp = &storageEl;
+		else if (pg_strcasecmp(defel->defname, "collatable") == 0)
+			defelp = &collatableEl;
 		else
 		{
 			/* WARNING, not ERROR, for historical backwards-compatibility */
@@ -287,7 +292,7 @@ DefineType(List *names, List *parameters)
 		Type		likeType;
 		Form_pg_type likeForm;
 
-		likeType = typenameType(NULL, defGetTypeName(likeTypeEl), NULL);
+		likeType = typenameType(NULL, defGetTypeName(likeTypeEl), NULL, NULL);
 		likeForm = (Form_pg_type) GETSTRUCT(likeType);
 		internalLength = likeForm->typlen;
 		byValue = likeForm->typbyval;
@@ -390,6 +395,8 @@ DefineType(List *names, List *parameters)
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 					 errmsg("storage \"%s\" not recognized", a)));
 	}
+	if (collatableEl)
+		collation = defGetBoolean(collatableEl) ? DEFAULT_COLLATION_OID : InvalidOid;
 
 	/*
 	 * make sure we have our required definitions
@@ -562,7 +569,8 @@ DefineType(List *names, List *parameters)
 				   storage,		/* TOAST strategy */
 				   -1,			/* typMod (Domains only) */
 				   0,			/* Array Dimensions of typbasetype */
-				   false);		/* Type NOT NULL */
+				   false,		/* Type NOT NULL */
+				   collation);
 
 	/*
 	 * Create the array type that goes with it.
@@ -601,7 +609,8 @@ DefineType(List *names, List *parameters)
 			   'x',				/* ARRAY is always toastable */
 			   -1,				/* typMod (Domains only) */
 			   0,				/* Array dimensions of typbasetype */
-			   false);			/* Type NOT NULL */
+			   false,			/* Type NOT NULL */
+			   collation);
 
 	pfree(array_type);
 }
@@ -640,7 +649,7 @@ RemoveTypes(DropStmt *drop)
 		typename = makeTypeNameFromNameList(names);
 
 		/* Use LookupTypeName here so that shell types can be removed. */
-		tup = LookupTypeName(NULL, typename, NULL);
+		tup = LookupTypeName(NULL, typename, NULL, NULL);
 		if (tup == NULL)
 		{
 			if (!drop->missing_ok)
@@ -767,6 +776,7 @@ DefineDomain(CreateDomainStmt *stmt)
 	Oid			old_type_oid;
 	Form_pg_type baseType;
 	int32		basetypeMod;
+	Oid			baseColl;
 
 	/* Convert list of names to a name and namespace */
 	domainNamespace = QualifiedNameGetCreationNamespace(stmt->domainname,
@@ -797,7 +807,7 @@ DefineDomain(CreateDomainStmt *stmt)
 	/*
 	 * Look up the base type.
 	 */
-	typeTup = typenameType(NULL, stmt->typeName, &basetypeMod);
+	typeTup = typenameType(NULL, stmt->typeName, &basetypeMod, &baseColl);
 	baseType = (Form_pg_type) GETSTRUCT(typeTup);
 	basetypeoid = HeapTupleGetOid(typeTup);
 
@@ -1040,7 +1050,8 @@ DefineDomain(CreateDomainStmt *stmt)
 				   storage,		/* TOAST strategy */
 				   basetypeMod, /* typeMod value */
 				   typNDims,	/* Array dimensions for base type */
-				   typNotNull); /* Type NOT NULL */
+				   typNotNull,	/* Type NOT NULL */
+				   baseColl);
 
 	/*
 	 * Process constraints which refer to the domain ID returned by TypeCreate
@@ -1149,7 +1160,8 @@ DefineEnum(CreateEnumStmt *stmt)
 				   'p',			/* TOAST strategy always plain */
 				   -1,			/* typMod (Domains only) */
 				   0,			/* Array dimensions of typbasetype */
-				   false);		/* Type NOT NULL */
+				   false,		/* Type NOT NULL */
+				   InvalidOid);	/* typcollation */
 
 	/* Enter the enum's values into pg_enum */
 	EnumValuesCreate(enumTypeOid, stmt->vals);
@@ -1188,7 +1200,8 @@ DefineEnum(CreateEnumStmt *stmt)
 			   'x',				/* ARRAY is always toastable */
 			   -1,				/* typMod (Domains only) */
 			   0,				/* Array dimensions of typbasetype */
-			   false);			/* Type NOT NULL */
+			   false,			/* Type NOT NULL */
+			   InvalidOid);		/* typcollation */
 
 	pfree(enumArrayName);
 }
@@ -2615,7 +2628,7 @@ AlterTypeOwner(List *names, Oid newOwnerId)
 	typename = makeTypeNameFromNameList(names);
 
 	/* Use LookupTypeName here so that shell types can be processed */
-	tup = LookupTypeName(NULL, typename, NULL);
+	tup = LookupTypeName(NULL, typename, NULL, NULL);
 	if (tup == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),

src/backend/commands/view.c

@@ -120,7 +120,8 @@ DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace)
 
 			def->colname = pstrdup(tle->resname);
 			def->typeName = makeTypeNameFromOid(exprType((Node *) tle->expr),
-											 exprTypmod((Node *) tle->expr));
+												exprTypmod((Node *) tle->expr),
+												exprCollation((Node *) tle->expr));
 			def->inhcount = 0;
 			def->is_local = true;
 			def->is_not_null = false;

src/backend/executor/execQual.c

@@ -166,6 +166,9 @@ static Datum ExecEvalFieldStore(FieldStoreState *fstate,
 static Datum ExecEvalRelabelType(GenericExprState *exprstate,
 					ExprContext *econtext,
 					bool *isNull, ExprDoneCond *isDone);
+static Datum ExecEvalCollateClause(GenericExprState *exprstate,
+					ExprContext *econtext,
+					bool *isNull, ExprDoneCond *isDone);
 static Datum ExecEvalCoerceViaIO(CoerceViaIOState *iostate,
 					ExprContext *econtext,
 					bool *isNull, ExprDoneCond *isDone);
@@ -1202,7 +1205,7 @@ init_fcache(Oid foid, FuncExprState *fcache,
 
 	/* Set up the primary fmgr lookup information */
 	fmgr_info_cxt(foid, &(fcache->func), fcacheCxt);
-	fcache->func.fn_expr = (Node *) fcache->xprstate.expr;
+	fmgr_info_expr((Node *) fcache->xprstate.expr, &(fcache->func));
 
 	/* Initialize the function call parameter struct as well */
 	InitFunctionCallInfoData(fcache->fcinfo_data, &(fcache->func),
@@ -4025,6 +4028,20 @@ ExecEvalRelabelType(GenericExprState *exprstate,
 	return ExecEvalExpr(exprstate->arg, econtext, isNull, isDone);
 }
 
+/* ----------------------------------------------------------------
+ *		ExecEvalCollateClause
+ *
+ *		Evaluate a CollateClause node.
+ * ----------------------------------------------------------------
+ */
+static Datum
+ExecEvalCollateClause(GenericExprState *exprstate,
+					ExprContext *econtext,
+					bool *isNull, ExprDoneCond *isDone)
+{
+	return ExecEvalExpr(exprstate->arg, econtext, isNull, isDone);
+}
+
 /* ----------------------------------------------------------------
  *		ExecEvalCoerceViaIO
  *
@@ -4114,7 +4131,7 @@ ExecEvalArrayCoerceExpr(ArrayCoerceExprState *astate,
 					  econtext->ecxt_per_query_memory);
 
 		/* Initialize additional info */
-		astate->elemfunc.fn_expr = (Node *) acoerce;
+		fmgr_info_expr((Node *) acoerce, &(astate->elemfunc));
 	}
 
 	/*
@@ -4484,6 +4501,16 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				state = (ExprState *) gstate;
 			}
 			break;
+		case T_CollateClause:
+			{
+				CollateClause *collate = (CollateClause *) node;
+				GenericExprState *gstate = makeNode(GenericExprState);
+
+				gstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalCollateClause;
+				gstate->arg = ExecInitExpr(collate->arg, parent);
+				state = (ExprState *) gstate;
+			}
+			break;
 		case T_CoerceViaIO:
 			{
 				CoerceViaIO *iocoerce = (CoerceViaIO *) node;
@@ -4657,6 +4684,7 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				List	   *outlist;
 				ListCell   *l;
 				ListCell   *l2;
+				ListCell   *l3;
 				int			i;
 
 				rstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalRowCompare;
@@ -4685,10 +4713,11 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				Assert(list_length(rcexpr->opfamilies) == nopers);
 				rstate->funcs = (FmgrInfo *) palloc(nopers * sizeof(FmgrInfo));
 				i = 0;
-				forboth(l, rcexpr->opnos, l2, rcexpr->opfamilies)
+				forthree(l, rcexpr->opnos, l2, rcexpr->opfamilies, l3, rcexpr->collids)
 				{
 					Oid			opno = lfirst_oid(l);
 					Oid			opfamily = lfirst_oid(l2);
+					Oid			collid = lfirst_oid(l3);
 					int			strategy;
 					Oid			lefttype;
 					Oid			righttype;
@@ -4710,6 +4739,7 @@ ExecInitExpr(Expr *node, PlanState *parent)
 					 * does this code.
 					 */
 					fmgr_info(proc, &(rstate->funcs[i]));
+					fmgr_info_collation(collid, &(rstate->funcs[i]));
 					i++;
 				}
 				state = (ExprState *) rstate;
@@ -4769,6 +4799,7 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				 * code.
 				 */
 				fmgr_info(typentry->cmp_proc, &(mstate->cfunc));
+				fmgr_info_collation(minmaxexpr->collid, &(mstate->cfunc));
 				state = (ExprState *) mstate;
 			}
 			break;

src/backend/executor/execTuples.c

@@ -937,11 +937,15 @@ ExecTypeFromTLInternal(List *targetList, bool hasoid, bool skipjunk)
 		if (skipjunk && tle->resjunk)
 			continue;
 		TupleDescInitEntry(typeInfo,
-						   cur_resno++,
+						   cur_resno,
 						   tle->resname,
 						   exprType((Node *) tle->expr),
 						   exprTypmod((Node *) tle->expr),
 						   0);
+		TupleDescInitEntryCollation(typeInfo,
+									cur_resno,
+									exprCollation((Node *) tle->expr));
+		cur_resno++;
 	}
 
 	return typeInfo;
@@ -969,11 +973,15 @@ ExecTypeFromExprList(List *exprList)
 		sprintf(fldname, "f%d", cur_resno);
 
 		TupleDescInitEntry(typeInfo,
-						   cur_resno++,
+						   cur_resno,
 						   fldname,
 						   exprType(e),
 						   exprTypmod(e),
 						   0);
+		TupleDescInitEntryCollation(typeInfo,
+									cur_resno,
+									exprCollation(e));
+		cur_resno++;
 	}
 
 	return typeInfo;

src/backend/executor/nodeAgg.c

@@ -140,6 +140,7 @@ typedef struct AggStatePerAggData
 	/* deconstructed sorting information (arrays of length numSortCols) */
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
+	Oid		   *sortCollations;
 	bool	   *sortNullsFirst;
 
 	/*
@@ -315,12 +316,14 @@ initialize_aggregates(AggState *aggstate,
 				(peraggstate->numInputs == 1) ?
 				tuplesort_begin_datum(peraggstate->evaldesc->attrs[0]->atttypid,
 									  peraggstate->sortOperators[0],
+									  peraggstate->sortCollations[0],
 									  peraggstate->sortNullsFirst[0],
 									  work_mem, false) :
 				tuplesort_begin_heap(peraggstate->evaldesc,
 									 peraggstate->numSortCols,
 									 peraggstate->sortColIdx,
 									 peraggstate->sortOperators,
+									 peraggstate->sortCollations,
 									 peraggstate->sortNullsFirst,
 									 work_mem, false);
 		}
@@ -1668,16 +1671,17 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 								aggref->aggtype,
 								transfn_oid,
 								finalfn_oid,
+								aggref->collid,
 								&transfnexpr,
 								&finalfnexpr);
 
 		fmgr_info(transfn_oid, &peraggstate->transfn);
-		peraggstate->transfn.fn_expr = (Node *) transfnexpr;
+		fmgr_info_expr((Node *) transfnexpr, &peraggstate->transfn);
 
 		if (OidIsValid(finalfn_oid))
 		{
 			fmgr_info(finalfn_oid, &peraggstate->finalfn);
-			peraggstate->finalfn.fn_expr = (Node *) finalfnexpr;
+			fmgr_info_expr((Node *) finalfnexpr, &peraggstate->finalfn);
 		}
 
 		get_typlenbyval(aggref->aggtype,
@@ -1786,6 +1790,8 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 				(AttrNumber *) palloc(numSortCols * sizeof(AttrNumber));
 			peraggstate->sortOperators =
 				(Oid *) palloc(numSortCols * sizeof(Oid));
+			peraggstate->sortCollations =
+				(Oid *) palloc(numSortCols * sizeof(Oid));
 			peraggstate->sortNullsFirst =
 				(bool *) palloc(numSortCols * sizeof(bool));
 
@@ -1801,6 +1807,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 
 				peraggstate->sortColIdx[i] = tle->resno;
 				peraggstate->sortOperators[i] = sortcl->sortop;
+				peraggstate->sortCollations[i] = exprCollation((Node *) tle->expr);
 				peraggstate->sortNullsFirst[i] = sortcl->nulls_first;
 				i++;
 			}

src/backend/executor/nodeFunctionscan.c

@@ -24,6 +24,7 @@
 
 #include "executor/nodeFunctionscan.h"
 #include "funcapi.h"
+#include "nodes/nodeFuncs.h"
 #include "utils/builtins.h"
 
 
@@ -185,12 +186,16 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
 						   funcrettype,
 						   -1,
 						   0);
+		TupleDescInitEntryCollation(tupdesc,
+									(AttrNumber) 1,
+									exprCollation(node->funcexpr));
 	}
 	else if (functypclass == TYPEFUNC_RECORD)
 	{
 		tupdesc = BuildDescFromLists(node->funccolnames,
 									 node->funccoltypes,
-									 node->funccoltypmods);
+									 node->funccoltypmods,
+									 node->funccolcollations);
 	}
 	else
 	{

src/backend/executor/nodeIndexscan.c

@@ -732,6 +732,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 		int			op_strategy;	/* operator's strategy number */
 		Oid			op_lefttype;	/* operator's declared input types */
 		Oid			op_righttype;
+		Oid			collation;
 		Expr	   *leftop;		/* expr on lhs of operator */
 		Expr	   *rightop;	/* expr on rhs ... */
 		AttrNumber	varattno;	/* att number used in scan */
@@ -831,6 +832,8 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 								   op_righttype,		/* strategy subtype */
 								   opfuncid,	/* reg proc to use */
 								   scanvalue);	/* constant */
+			ScanKeyEntryInitializeCollation(this_scan_key,
+											((OpExpr *) clause)->collid);
 		}
 		else if (IsA(clause, RowCompareExpr))
 		{
@@ -839,6 +842,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 			ListCell   *largs_cell = list_head(rc->largs);
 			ListCell   *rargs_cell = list_head(rc->rargs);
 			ListCell   *opnos_cell = list_head(rc->opnos);
+			ListCell   *collids_cell = list_head(rc->collids);
 			ScanKey		first_sub_key;
 			int			n_sub_key;
 
@@ -897,6 +901,9 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 											 op_righttype,
 											 BTORDER_PROC);
 
+				collation = lfirst_oid(collids_cell);
+				collids_cell = lnext(collids_cell);
+
 				/*
 				 * rightop is the constant or variable comparison value
 				 */
@@ -952,6 +959,8 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 									   op_righttype,	/* strategy subtype */
 									   opfuncid,		/* reg proc to use */
 									   scanvalue);		/* constant */
+				ScanKeyEntryInitializeCollation(this_sub_key,
+												collation);
 				n_sub_key++;
 			}
 
@@ -1035,6 +1044,8 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 								   op_righttype,		/* strategy subtype */
 								   opfuncid,	/* reg proc to use */
 								   (Datum) 0);	/* constant */
+			ScanKeyEntryInitializeCollation(this_scan_key,
+											saop->collid);
 		}
 		else if (IsA(clause, NullTest))
 		{

src/backend/executor/nodeMergeAppend.c

@@ -150,6 +150,9 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags)
 					sortFunction,
 					(Datum) 0);
 
+		ScanKeyEntryInitializeCollation(&mergestate->ms_scankeys[i],
+										node->collations[i]);
+
 		/* However, we use btree's conventions for encoding directionality */
 		if (reverse)
 			mergestate->ms_scankeys[i].sk_flags |= SK_BT_DESC;

src/backend/executor/nodeMergejoin.c

@@ -180,6 +180,7 @@ typedef enum
 static MergeJoinClause
 MJExamineQuals(List *mergeclauses,
 			   Oid *mergefamilies,
+			   Oid *mergecollations,
 			   int *mergestrategies,
 			   bool *mergenullsfirst,
 			   PlanState *parent)
@@ -197,6 +198,7 @@ MJExamineQuals(List *mergeclauses,
 		OpExpr	   *qual = (OpExpr *) lfirst(cl);
 		MergeJoinClause clause = &clauses[iClause];
 		Oid			opfamily = mergefamilies[iClause];
+		Oid			collation = mergecollations[iClause];
 		StrategyNumber opstrategy = mergestrategies[iClause];
 		bool		nulls_first = mergenullsfirst[iClause];
 		int			op_strategy;
@@ -240,6 +242,7 @@ MJExamineQuals(List *mergeclauses,
 
 		/* Set up the fmgr lookup information */
 		fmgr_info(cmpproc, &(clause->cmpfinfo));
+		fmgr_info_collation(collation, &(clause->cmpfinfo));
 
 		/* Fill the additional comparison-strategy flags */
 		if (opstrategy == BTLessStrategyNumber)
@@ -1636,6 +1639,7 @@ ExecInitMergeJoin(MergeJoin *node, EState *estate, int eflags)
 	mergestate->mj_NumClauses = list_length(node->mergeclauses);
 	mergestate->mj_Clauses = MJExamineQuals(node->mergeclauses,
 											node->mergeFamilies,
+											node->mergeCollations,
 											node->mergeStrategies,
 											node->mergeNullsFirst,
 											(PlanState *) mergestate);

src/backend/executor/nodeSort.c

@@ -86,6 +86,7 @@ ExecSort(SortState *node)
 											  plannode->numCols,
 											  plannode->sortColIdx,
 											  plannode->sortOperators,
+											  plannode->collations,
 											  plannode->nullsFirst,
 											  work_mem,
 											  node->randomAccess);

src/backend/executor/nodeSubplan.c

@@ -831,7 +831,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 
 			/* Lookup the equality function (potentially cross-type) */
 			fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
-			sstate->cur_eq_funcs[i - 1].fn_expr = (Node *) opexpr;
+			fmgr_info_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]);
 
 			/* Look up the equality function for the RHS type */
 			if (!get_compatible_hash_operators(opexpr->opno,

src/backend/executor/nodeWindowAgg.c

@@ -1561,7 +1561,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 
 		fmgr_info_cxt(wfunc->winfnoid, &perfuncstate->flinfo,
 					  econtext->ecxt_per_query_memory);
-		perfuncstate->flinfo.fn_expr = (Node *) wfunc;
+		fmgr_info_expr((Node *) wfunc, &perfuncstate->flinfo);
 		get_typlenbyval(wfunc->wintype,
 						&perfuncstate->resulttypeLen,
 						&perfuncstate->resulttypeByVal);
@@ -1794,16 +1794,17 @@ initialize_peragg(WindowAggState *winstate, WindowFunc *wfunc,
 							wfunc->wintype,
 							transfn_oid,
 							finalfn_oid,
+							wfunc->collid,
 							&transfnexpr,
 							&finalfnexpr);
 
 	fmgr_info(transfn_oid, &peraggstate->transfn);
-	peraggstate->transfn.fn_expr = (Node *) transfnexpr;
+	fmgr_info_expr((Node *) transfnexpr, &peraggstate->transfn);
 
 	if (OidIsValid(finalfn_oid))
 	{
 		fmgr_info(finalfn_oid, &peraggstate->finalfn);
-		peraggstate->finalfn.fn_expr = (Node *) finalfnexpr;
+		fmgr_info_expr((Node *) finalfnexpr, &peraggstate->finalfn);
 	}
 
 	get_typlenbyval(wfunc->wintype,

src/backend/nodes/copyfuncs.c

@@ -223,6 +223,7 @@ _copyMergeAppend(MergeAppend *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(sortColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(sortOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(collations, from->numCols * sizeof(Oid));
 	COPY_POINTER_FIELD(nullsFirst, from->numCols * sizeof(bool));
 
 	return newnode;
@@ -479,6 +480,7 @@ _copyFunctionScan(FunctionScan *from)
 	COPY_NODE_FIELD(funccolnames);
 	COPY_NODE_FIELD(funccoltypes);
 	COPY_NODE_FIELD(funccoltypmods);
+	COPY_NODE_FIELD(funccolcollations);
 
 	return newnode;
 }
@@ -622,6 +624,7 @@ _copyMergeJoin(MergeJoin *from)
 	COPY_NODE_FIELD(mergeclauses);
 	numCols = list_length(from->mergeclauses);
 	COPY_POINTER_FIELD(mergeFamilies, numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(mergeCollations, numCols * sizeof(Oid));
 	COPY_POINTER_FIELD(mergeStrategies, numCols * sizeof(int));
 	COPY_POINTER_FIELD(mergeNullsFirst, numCols * sizeof(bool));
 
@@ -683,6 +686,7 @@ _copySort(Sort *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(sortColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(sortOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(collations, from->numCols * sizeof(Oid));
 	COPY_POINTER_FIELD(nullsFirst, from->numCols * sizeof(bool));
 
 	return newnode;
@@ -998,6 +1002,7 @@ _copyVar(Var *from)
 	COPY_SCALAR_FIELD(varattno);
 	COPY_SCALAR_FIELD(vartype);
 	COPY_SCALAR_FIELD(vartypmod);
+	COPY_SCALAR_FIELD(varcollid);
 	COPY_SCALAR_FIELD(varlevelsup);
 	COPY_SCALAR_FIELD(varnoold);
 	COPY_SCALAR_FIELD(varoattno);
@@ -1016,6 +1021,7 @@ _copyConst(Const *from)
 
 	COPY_SCALAR_FIELD(consttype);
 	COPY_SCALAR_FIELD(consttypmod);
+	COPY_SCALAR_FIELD(constcollid);
 	COPY_SCALAR_FIELD(constlen);
 
 	if (from->constbyval || from->constisnull)
@@ -1055,6 +1061,7 @@ _copyParam(Param *from)
 	COPY_SCALAR_FIELD(paramid);
 	COPY_SCALAR_FIELD(paramtype);
 	COPY_SCALAR_FIELD(paramtypmod);
+	COPY_SCALAR_FIELD(paramcollation);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1075,6 +1082,7 @@ _copyAggref(Aggref *from)
 	COPY_NODE_FIELD(aggdistinct);
 	COPY_SCALAR_FIELD(aggstar);
 	COPY_SCALAR_FIELD(agglevelsup);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1094,6 +1102,7 @@ _copyWindowFunc(WindowFunc *from)
 	COPY_SCALAR_FIELD(winref);
 	COPY_SCALAR_FIELD(winstar);
 	COPY_SCALAR_FIELD(winagg);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1110,6 +1119,7 @@ _copyArrayRef(ArrayRef *from)
 	COPY_SCALAR_FIELD(refarraytype);
 	COPY_SCALAR_FIELD(refelemtype);
 	COPY_SCALAR_FIELD(reftypmod);
+	COPY_SCALAR_FIELD(refcollid);
 	COPY_NODE_FIELD(refupperindexpr);
 	COPY_NODE_FIELD(reflowerindexpr);
 	COPY_NODE_FIELD(refexpr);
@@ -1131,6 +1141,7 @@ _copyFuncExpr(FuncExpr *from)
 	COPY_SCALAR_FIELD(funcretset);
 	COPY_SCALAR_FIELD(funcformat);
 	COPY_NODE_FIELD(args);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1165,6 +1176,7 @@ _copyOpExpr(OpExpr *from)
 	COPY_SCALAR_FIELD(opresulttype);
 	COPY_SCALAR_FIELD(opretset);
 	COPY_NODE_FIELD(args);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1183,6 +1195,7 @@ _copyDistinctExpr(DistinctExpr *from)
 	COPY_SCALAR_FIELD(opresulttype);
 	COPY_SCALAR_FIELD(opretset);
 	COPY_NODE_FIELD(args);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1200,6 +1213,7 @@ _copyScalarArrayOpExpr(ScalarArrayOpExpr *from)
 	COPY_SCALAR_FIELD(opfuncid);
 	COPY_SCALAR_FIELD(useOr);
 	COPY_NODE_FIELD(args);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1252,6 +1266,7 @@ _copySubPlan(SubPlan *from)
 	COPY_STRING_FIELD(plan_name);
 	COPY_SCALAR_FIELD(firstColType);
 	COPY_SCALAR_FIELD(firstColTypmod);
+	COPY_SCALAR_FIELD(firstColCollation);
 	COPY_SCALAR_FIELD(useHashTable);
 	COPY_SCALAR_FIELD(unknownEqFalse);
 	COPY_NODE_FIELD(setParam);
@@ -1288,6 +1303,7 @@ _copyFieldSelect(FieldSelect *from)
 	COPY_SCALAR_FIELD(fieldnum);
 	COPY_SCALAR_FIELD(resulttype);
 	COPY_SCALAR_FIELD(resulttypmod);
+	COPY_SCALAR_FIELD(resultcollation);
 
 	return newnode;
 }
@@ -1385,6 +1401,7 @@ _copyCaseExpr(CaseExpr *from)
 	CaseExpr   *newnode = makeNode(CaseExpr);
 
 	COPY_SCALAR_FIELD(casetype);
+	COPY_SCALAR_FIELD(casecollation);
 	COPY_NODE_FIELD(arg);
 	COPY_NODE_FIELD(args);
 	COPY_NODE_FIELD(defresult);
@@ -1418,6 +1435,7 @@ _copyCaseTestExpr(CaseTestExpr *from)
 
 	COPY_SCALAR_FIELD(typeId);
 	COPY_SCALAR_FIELD(typeMod);
+	COPY_SCALAR_FIELD(collation);
 
 	return newnode;
 }
@@ -1467,6 +1485,7 @@ _copyRowCompareExpr(RowCompareExpr *from)
 	COPY_SCALAR_FIELD(rctype);
 	COPY_NODE_FIELD(opnos);
 	COPY_NODE_FIELD(opfamilies);
+	COPY_NODE_FIELD(collids);
 	COPY_NODE_FIELD(largs);
 	COPY_NODE_FIELD(rargs);
 
@@ -1482,6 +1501,7 @@ _copyCoalesceExpr(CoalesceExpr *from)
 	CoalesceExpr *newnode = makeNode(CoalesceExpr);
 
 	COPY_SCALAR_FIELD(coalescetype);
+	COPY_SCALAR_FIELD(coalescecollation);
 	COPY_NODE_FIELD(args);
 	COPY_LOCATION_FIELD(location);
 
@@ -1499,6 +1519,7 @@ _copyMinMaxExpr(MinMaxExpr *from)
 	COPY_SCALAR_FIELD(minmaxtype);
 	COPY_SCALAR_FIELD(op);
 	COPY_NODE_FIELD(args);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1614,6 +1635,7 @@ _copySetToDefault(SetToDefault *from)
 
 	COPY_SCALAR_FIELD(typeId);
 	COPY_SCALAR_FIELD(typeMod);
+	COPY_SCALAR_FIELD(collid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -1719,6 +1741,7 @@ _copyPathKey(PathKey *from)
 	/* EquivalenceClasses are never moved, so just shallow-copy the pointer */
 	COPY_SCALAR_FIELD(pk_eclass);
 	COPY_SCALAR_FIELD(pk_opfamily);
+	COPY_SCALAR_FIELD(pk_collation);
 	COPY_SCALAR_FIELD(pk_strategy);
 	COPY_SCALAR_FIELD(pk_nulls_first);
 
@@ -1871,12 +1894,14 @@ _copyRangeTblEntry(RangeTblEntry *from)
 	COPY_NODE_FIELD(funcexpr);
 	COPY_NODE_FIELD(funccoltypes);
 	COPY_NODE_FIELD(funccoltypmods);
+	COPY_NODE_FIELD(funccolcollations);
 	COPY_NODE_FIELD(values_lists);
 	COPY_STRING_FIELD(ctename);
 	COPY_SCALAR_FIELD(ctelevelsup);
 	COPY_SCALAR_FIELD(self_reference);
 	COPY_NODE_FIELD(ctecoltypes);
 	COPY_NODE_FIELD(ctecoltypmods);
+	COPY_NODE_FIELD(ctecolcollations);
 	COPY_NODE_FIELD(alias);
 	COPY_NODE_FIELD(eref);
 	COPY_SCALAR_FIELD(inh);
@@ -1960,6 +1985,7 @@ _copyCommonTableExpr(CommonTableExpr *from)
 	COPY_NODE_FIELD(ctecolnames);
 	COPY_NODE_FIELD(ctecoltypes);
 	COPY_NODE_FIELD(ctecoltypmods);
+	COPY_NODE_FIELD(ctecolcollations);
 
 	return newnode;
 }
@@ -2114,6 +2140,8 @@ _copyTypeName(TypeName *from)
 	COPY_NODE_FIELD(typmods);
 	COPY_SCALAR_FIELD(typemod);
 	COPY_NODE_FIELD(arrayBounds);
+	COPY_NODE_FIELD(collnames);
+	COPY_SCALAR_FIELD(collOid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -2185,6 +2213,19 @@ _copyTypeCast(TypeCast *from)
 	return newnode;
 }
 
+static CollateClause *
+_copyCollateClause(CollateClause *from)
+{
+	CollateClause   *newnode = makeNode(CollateClause);
+
+	COPY_NODE_FIELD(arg);
+	COPY_NODE_FIELD(collnames);
+	COPY_SCALAR_FIELD(collOid);
+	COPY_LOCATION_FIELD(location);
+
+	return newnode;
+}
+
 static IndexElem *
 _copyIndexElem(IndexElem *from)
 {
@@ -2193,6 +2234,7 @@ _copyIndexElem(IndexElem *from)
 	COPY_STRING_FIELD(name);
 	COPY_NODE_FIELD(expr);
 	COPY_STRING_FIELD(indexcolname);
+	COPY_NODE_FIELD(collation);
 	COPY_NODE_FIELD(opclass);
 	COPY_SCALAR_FIELD(ordering);
 	COPY_SCALAR_FIELD(nulls_ordering);
@@ -2403,6 +2445,7 @@ _copySetOperationStmt(SetOperationStmt *from)
 	COPY_NODE_FIELD(rarg);
 	COPY_NODE_FIELD(colTypes);
 	COPY_NODE_FIELD(colTypmods);
+	COPY_NODE_FIELD(colCollations);
 	COPY_NODE_FIELD(groupClauses);
 
 	return newnode;
@@ -4328,6 +4371,9 @@ copyObject(void *from)
 		case T_TypeCast:
 			retval = _copyTypeCast(from);
 			break;
+		case T_CollateClause:
+			retval = _copyCollateClause(from);
+			break;
 		case T_SortBy:
 			retval = _copySortBy(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -137,6 +137,7 @@ _equalVar(Var *a, Var *b)
 	COMPARE_SCALAR_FIELD(varattno);
 	COMPARE_SCALAR_FIELD(vartype);
 	COMPARE_SCALAR_FIELD(vartypmod);
+	COMPARE_SCALAR_FIELD(varcollid);
 	COMPARE_SCALAR_FIELD(varlevelsup);
 	COMPARE_SCALAR_FIELD(varnoold);
 	COMPARE_SCALAR_FIELD(varoattno);
@@ -150,6 +151,7 @@ _equalConst(Const *a, Const *b)
 {
 	COMPARE_SCALAR_FIELD(consttype);
 	COMPARE_SCALAR_FIELD(consttypmod);
+	COMPARE_SCALAR_FIELD(constcollid);
 	COMPARE_SCALAR_FIELD(constlen);
 	COMPARE_SCALAR_FIELD(constisnull);
 	COMPARE_SCALAR_FIELD(constbyval);
@@ -172,6 +174,7 @@ _equalParam(Param *a, Param *b)
 	COMPARE_SCALAR_FIELD(paramid);
 	COMPARE_SCALAR_FIELD(paramtype);
 	COMPARE_SCALAR_FIELD(paramtypmod);
+	COMPARE_SCALAR_FIELD(paramcollation);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -187,6 +190,7 @@ _equalAggref(Aggref *a, Aggref *b)
 	COMPARE_NODE_FIELD(aggdistinct);
 	COMPARE_SCALAR_FIELD(aggstar);
 	COMPARE_SCALAR_FIELD(agglevelsup);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -201,6 +205,7 @@ _equalWindowFunc(WindowFunc *a, WindowFunc *b)
 	COMPARE_SCALAR_FIELD(winref);
 	COMPARE_SCALAR_FIELD(winstar);
 	COMPARE_SCALAR_FIELD(winagg);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -212,6 +217,7 @@ _equalArrayRef(ArrayRef *a, ArrayRef *b)
 	COMPARE_SCALAR_FIELD(refarraytype);
 	COMPARE_SCALAR_FIELD(refelemtype);
 	COMPARE_SCALAR_FIELD(reftypmod);
+	COMPARE_SCALAR_FIELD(refcollid);
 	COMPARE_NODE_FIELD(refupperindexpr);
 	COMPARE_NODE_FIELD(reflowerindexpr);
 	COMPARE_NODE_FIELD(refexpr);
@@ -237,6 +243,7 @@ _equalFuncExpr(FuncExpr *a, FuncExpr *b)
 		return false;
 
 	COMPARE_NODE_FIELD(args);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -272,6 +279,7 @@ _equalOpExpr(OpExpr *a, OpExpr *b)
 	COMPARE_SCALAR_FIELD(opresulttype);
 	COMPARE_SCALAR_FIELD(opretset);
 	COMPARE_NODE_FIELD(args);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -296,6 +304,7 @@ _equalDistinctExpr(DistinctExpr *a, DistinctExpr *b)
 	COMPARE_SCALAR_FIELD(opresulttype);
 	COMPARE_SCALAR_FIELD(opretset);
 	COMPARE_NODE_FIELD(args);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -319,6 +328,7 @@ _equalScalarArrayOpExpr(ScalarArrayOpExpr *a, ScalarArrayOpExpr *b)
 
 	COMPARE_SCALAR_FIELD(useOr);
 	COMPARE_NODE_FIELD(args);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -356,6 +366,7 @@ _equalSubPlan(SubPlan *a, SubPlan *b)
 	COMPARE_STRING_FIELD(plan_name);
 	COMPARE_SCALAR_FIELD(firstColType);
 	COMPARE_SCALAR_FIELD(firstColTypmod);
+	COMPARE_SCALAR_FIELD(firstColCollation);
 	COMPARE_SCALAR_FIELD(useHashTable);
 	COMPARE_SCALAR_FIELD(unknownEqFalse);
 	COMPARE_NODE_FIELD(setParam);
@@ -382,6 +393,7 @@ _equalFieldSelect(FieldSelect *a, FieldSelect *b)
 	COMPARE_SCALAR_FIELD(fieldnum);
 	COMPARE_SCALAR_FIELD(resulttype);
 	COMPARE_SCALAR_FIELD(resulttypmod);
+	COMPARE_SCALAR_FIELD(resultcollation);
 
 	return true;
 }
@@ -485,6 +497,7 @@ static bool
 _equalCaseExpr(CaseExpr *a, CaseExpr *b)
 {
 	COMPARE_SCALAR_FIELD(casetype);
+	COMPARE_SCALAR_FIELD(casecollation);
 	COMPARE_NODE_FIELD(arg);
 	COMPARE_NODE_FIELD(args);
 	COMPARE_NODE_FIELD(defresult);
@@ -508,6 +521,7 @@ _equalCaseTestExpr(CaseTestExpr *a, CaseTestExpr *b)
 {
 	COMPARE_SCALAR_FIELD(typeId);
 	COMPARE_SCALAR_FIELD(typeMod);
+	COMPARE_SCALAR_FIELD(collation);
 
 	return true;
 }
@@ -551,6 +565,7 @@ _equalRowCompareExpr(RowCompareExpr *a, RowCompareExpr *b)
 	COMPARE_SCALAR_FIELD(rctype);
 	COMPARE_NODE_FIELD(opnos);
 	COMPARE_NODE_FIELD(opfamilies);
+	COMPARE_NODE_FIELD(collids);
 	COMPARE_NODE_FIELD(largs);
 	COMPARE_NODE_FIELD(rargs);
 
@@ -561,6 +576,7 @@ static bool
 _equalCoalesceExpr(CoalesceExpr *a, CoalesceExpr *b)
 {
 	COMPARE_SCALAR_FIELD(coalescetype);
+	COMPARE_SCALAR_FIELD(coalescecollation);
 	COMPARE_NODE_FIELD(args);
 	COMPARE_LOCATION_FIELD(location);
 
@@ -573,6 +589,7 @@ _equalMinMaxExpr(MinMaxExpr *a, MinMaxExpr *b)
 	COMPARE_SCALAR_FIELD(minmaxtype);
 	COMPARE_SCALAR_FIELD(op);
 	COMPARE_NODE_FIELD(args);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -673,6 +690,7 @@ _equalSetToDefault(SetToDefault *a, SetToDefault *b)
 {
 	COMPARE_SCALAR_FIELD(typeId);
 	COMPARE_SCALAR_FIELD(typeMod);
+	COMPARE_SCALAR_FIELD(collid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -759,6 +777,7 @@ _equalPathKey(PathKey *a, PathKey *b)
 	if (a_eclass != b_eclass)
 		return false;
 	COMPARE_SCALAR_FIELD(pk_opfamily);
+	COMPARE_SCALAR_FIELD(pk_collation);
 	COMPARE_SCALAR_FIELD(pk_strategy);
 	COMPARE_SCALAR_FIELD(pk_nulls_first);
 
@@ -965,6 +984,7 @@ _equalSetOperationStmt(SetOperationStmt *a, SetOperationStmt *b)
 	COMPARE_NODE_FIELD(rarg);
 	COMPARE_NODE_FIELD(colTypes);
 	COMPARE_NODE_FIELD(colTypmods);
+	COMPARE_NODE_FIELD(colCollations);
 	COMPARE_NODE_FIELD(groupClauses);
 
 	return true;
@@ -2079,6 +2099,8 @@ _equalTypeName(TypeName *a, TypeName *b)
 	COMPARE_NODE_FIELD(typmods);
 	COMPARE_SCALAR_FIELD(typemod);
 	COMPARE_NODE_FIELD(arrayBounds);
+	COMPARE_NODE_FIELD(collnames);
+	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -2094,6 +2116,17 @@ _equalTypeCast(TypeCast *a, TypeCast *b)
 	return true;
 }
 
+static bool
+_equalCollateClause(CollateClause *a, CollateClause *b)
+{
+	COMPARE_NODE_FIELD(arg);
+	COMPARE_NODE_FIELD(collnames);
+	COMPARE_SCALAR_FIELD(collOid);
+	COMPARE_LOCATION_FIELD(location);
+
+	return true;
+}
+
 static bool
 _equalSortBy(SortBy *a, SortBy *b)
 {
@@ -2146,6 +2179,7 @@ _equalIndexElem(IndexElem *a, IndexElem *b)
 	COMPARE_STRING_FIELD(name);
 	COMPARE_NODE_FIELD(expr);
 	COMPARE_STRING_FIELD(indexcolname);
+	COMPARE_NODE_FIELD(collation);
 	COMPARE_NODE_FIELD(opclass);
 	COMPARE_SCALAR_FIELD(ordering);
 	COMPARE_SCALAR_FIELD(nulls_ordering);
@@ -2229,12 +2263,14 @@ _equalRangeTblEntry(RangeTblEntry *a, RangeTblEntry *b)
 	COMPARE_NODE_FIELD(funcexpr);
 	COMPARE_NODE_FIELD(funccoltypes);
 	COMPARE_NODE_FIELD(funccoltypmods);
+	COMPARE_NODE_FIELD(funccolcollations);
 	COMPARE_NODE_FIELD(values_lists);
 	COMPARE_STRING_FIELD(ctename);
 	COMPARE_SCALAR_FIELD(ctelevelsup);
 	COMPARE_SCALAR_FIELD(self_reference);
 	COMPARE_NODE_FIELD(ctecoltypes);
 	COMPARE_NODE_FIELD(ctecoltypmods);
+	COMPARE_NODE_FIELD(ctecolcollations);
 	COMPARE_NODE_FIELD(alias);
 	COMPARE_NODE_FIELD(eref);
 	COMPARE_SCALAR_FIELD(inh);
@@ -2308,6 +2344,7 @@ _equalCommonTableExpr(CommonTableExpr *a, CommonTableExpr *b)
 	COMPARE_NODE_FIELD(ctecolnames);
 	COMPARE_NODE_FIELD(ctecoltypes);
 	COMPARE_NODE_FIELD(ctecoltypmods);
+	COMPARE_NODE_FIELD(ctecolcollations);
 
 	return true;
 }
@@ -2941,6 +2978,9 @@ equal(void *a, void *b)
 		case T_TypeCast:
 			retval = _equalTypeCast(a, b);
 			break;
+		case T_CollateClause:
+			retval = _equalCollateClause(a, b);
+			break;
 		case T_SortBy:
 			retval = _equalSortBy(a, b);
 			break;

src/backend/nodes/makefuncs.c

@@ -67,6 +67,7 @@ makeVar(Index varno,
 		AttrNumber varattno,
 		Oid vartype,
 		int32 vartypmod,
+		Oid varcollid,
 		Index varlevelsup)
 {
 	Var		   *var = makeNode(Var);
@@ -75,6 +76,7 @@ makeVar(Index varno,
 	var->varattno = varattno;
 	var->vartype = vartype;
 	var->vartypmod = vartypmod;
+	var->varcollid = varcollid;
 	var->varlevelsup = varlevelsup;
 
 	/*
@@ -105,6 +107,7 @@ makeVarFromTargetEntry(Index varno,
 				   tle->resno,
 				   exprType((Node *) tle->expr),
 				   exprTypmod((Node *) tle->expr),
+				   exprCollation((Node *) tle->expr),
 				   0);
 }
 
@@ -139,6 +142,7 @@ makeWholeRowVar(RangeTblEntry *rte,
 							 InvalidAttrNumber,
 							 toid,
 							 -1,
+							 InvalidOid,
 							 varlevelsup);
 			break;
 		case RTE_FUNCTION:
@@ -150,6 +154,7 @@ makeWholeRowVar(RangeTblEntry *rte,
 								 InvalidAttrNumber,
 								 toid,
 								 -1,
+								 InvalidOid,
 								 varlevelsup);
 			}
 			else
@@ -164,6 +169,7 @@ makeWholeRowVar(RangeTblEntry *rte,
 								 1,
 								 toid,
 								 -1,
+								 InvalidOid,
 								 varlevelsup);
 			}
 			break;
@@ -174,6 +180,7 @@ makeWholeRowVar(RangeTblEntry *rte,
 							 InvalidAttrNumber,
 							 toid,
 							 -1,
+							 InvalidOid,
 							 varlevelsup);
 			break;
 		default:
@@ -188,6 +195,7 @@ makeWholeRowVar(RangeTblEntry *rte,
 							 InvalidAttrNumber,
 							 RECORDOID,
 							 -1,
+							 InvalidOid,
 							 varlevelsup);
 			break;
 	}
@@ -272,6 +280,7 @@ makeConst(Oid consttype,
 
 	cnst->consttype = consttype;
 	cnst->consttypmod = consttypmod;
+	cnst->constcollid = get_typcollation(consttype);
 	cnst->constlen = constlen;
 	cnst->constvalue = constvalue;
 	cnst->constisnull = constisnull;
@@ -418,15 +427,16 @@ makeTypeNameFromNameList(List *names)
 
 /*
  * makeTypeNameFromOid -
- *	build a TypeName node to represent a type already known by OID/typmod.
+ *	build a TypeName node to represent a type already known by OID/typmod/collation.
  */
 TypeName *
-makeTypeNameFromOid(Oid typeOid, int32 typmod)
+makeTypeNameFromOid(Oid typeOid, int32 typmod, Oid collOid)
 {
 	TypeName   *n = makeNode(TypeName);
 
 	n->typeOid = typeOid;
 	n->typemod = typmod;
+	n->collOid = collOid;
 	n->location = -1;
 	return n;
 }
@@ -438,7 +448,7 @@ makeTypeNameFromOid(Oid typeOid, int32 typmod)
  * The argument expressions must have been transformed already.
  */
 FuncExpr *
-makeFuncExpr(Oid funcid, Oid rettype, List *args, CoercionForm fformat)
+makeFuncExpr(Oid funcid, Oid rettype, List *args, Oid collid, CoercionForm fformat)
 {
 	FuncExpr   *funcexpr;
 
@@ -448,6 +458,7 @@ makeFuncExpr(Oid funcid, Oid rettype, List *args, CoercionForm fformat)
 	funcexpr->funcretset = false;		/* only allowed case here */
 	funcexpr->funcformat = fformat;
 	funcexpr->args = args;
+	funcexpr->collid = collid;
 	funcexpr->location = -1;
 
 	return funcexpr;

src/backend/nodes/nodeFuncs.c

@@ -14,6 +14,7 @@
  */
 #include "postgres.h"
 
+#include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
@@ -161,6 +162,9 @@ exprType(Node *expr)
 		case T_RelabelType:
 			type = ((RelabelType *) expr)->resulttype;
 			break;
+		case T_CollateClause:
+			type = exprType((Node *) ((CollateClause *) expr)->arg);
+			break;
 		case T_CoerceViaIO:
 			type = ((CoerceViaIO *) expr)->resulttype;
 			break;
@@ -459,6 +463,215 @@ exprTypmod(Node *expr)
 	return -1;
 }
 
+/*
+ *	exprCollation -
+ *	  returns the Oid of the collation of the expression's result.
+ */
+Oid
+exprCollation(Node *expr)
+{
+	Oid			coll;
+
+	if (!expr)
+		return InvalidOid;
+
+	switch (nodeTag(expr))
+	{
+		case T_Var:
+			coll = ((Var *) expr)->varcollid;
+			break;
+		case T_Const:
+			coll = ((Const *) expr)->constcollid;
+			break;
+		case T_Param:
+			coll = ((Param *) expr)->paramcollation;
+			break;
+		case T_Aggref:
+			coll = ((Aggref *) expr)->collid;
+			break;
+		case T_WindowFunc:
+			coll = ((WindowFunc *) expr)->collid;
+			break;
+		case T_ArrayRef:
+			coll = ((ArrayRef *) expr)->refcollid;
+			break;
+		case T_FuncExpr:
+			coll = ((FuncExpr *) expr)->collid;
+			break;
+		case T_NamedArgExpr:
+			coll = exprCollation((Node *) ((NamedArgExpr *) expr)->arg);
+			break;
+		case T_OpExpr:
+			coll = ((OpExpr *) expr)->collid;
+			break;
+		case T_DistinctExpr:
+			coll = ((DistinctExpr *) expr)->collid;
+			break;
+		case T_ScalarArrayOpExpr:
+			coll = ((ScalarArrayOpExpr *) expr)->collid;
+			break;
+		case T_BoolExpr:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_SubLink:
+			{
+				SubLink    *sublink = (SubLink *) expr;
+
+				if (sublink->subLinkType == EXPR_SUBLINK ||
+					sublink->subLinkType == ARRAY_SUBLINK)
+				{
+					/* get the collation of the subselect's first target column */
+					Query	   *qtree = (Query *) sublink->subselect;
+					TargetEntry *tent;
+
+					if (!qtree || !IsA(qtree, Query))
+						elog(ERROR, "cannot get collation for untransformed sublink");
+					tent = (TargetEntry *) linitial(qtree->targetList);
+					Assert(IsA(tent, TargetEntry));
+					Assert(!tent->resjunk);
+					coll = exprCollation((Node *) tent->expr);
+					/* note we don't need to care if it's an array */
+				}
+				else
+					coll = InvalidOid;
+			}
+			break;
+		case T_SubPlan:
+			{
+				SubPlan    *subplan = (SubPlan *) expr;
+
+				if (subplan->subLinkType == EXPR_SUBLINK ||
+					subplan->subLinkType == ARRAY_SUBLINK)
+				{
+					/* get the collation of the subselect's first target column */
+					/* note we don't need to care if it's an array */
+					coll = subplan->firstColCollation;
+				}
+				else
+				{
+					/* for all other subplan types, result is boolean */
+					coll = InvalidOid;
+				}
+			}
+			break;
+		case T_AlternativeSubPlan:
+			{
+				AlternativeSubPlan *asplan = (AlternativeSubPlan *) expr;
+
+				/* subplans should all return the same thing */
+				coll = exprCollation((Node *) linitial(asplan->subplans));
+			}
+			break;
+		case T_FieldSelect:
+			coll = ((FieldSelect *) expr)->resultcollation;
+			break;
+		case T_FieldStore:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_RelabelType:
+			coll = exprCollation((Node *) ((RelabelType *) expr)->arg);
+			break;
+		case T_CollateClause:
+			coll = ((CollateClause *) expr)->collOid;
+			break;
+		case T_CoerceViaIO:
+		{
+			CoerceViaIO *cvio = (CoerceViaIO *) expr;
+			coll = coercion_expression_result_collation(cvio->resulttype, (Node *) cvio->arg);
+			break;
+		}
+		case T_ArrayCoerceExpr:
+		{
+			ArrayCoerceExpr *ace = (ArrayCoerceExpr *) expr;
+			coll = coercion_expression_result_collation(ace->resulttype, (Node *) ace->arg);
+			break;
+		}
+		case T_ConvertRowtypeExpr:
+		{
+			ConvertRowtypeExpr *cre = (ConvertRowtypeExpr *) expr;
+			coll = coercion_expression_result_collation(cre->resulttype, (Node *) cre->arg);
+			break;
+		}
+		case T_CaseExpr:
+			coll = ((CaseExpr *) expr)->casecollation;
+			break;
+		case T_CaseTestExpr:
+			coll = ((CaseTestExpr *) expr)->collation;
+			break;
+		case T_ArrayExpr:
+			coll = get_typcollation(((ArrayExpr *) expr)->array_typeid);
+			break;
+		case T_RowExpr:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_RowCompareExpr:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_CoalesceExpr:
+			coll = ((CoalesceExpr *) expr)->coalescecollation;
+			break;
+		case T_MinMaxExpr:
+			coll = ((MinMaxExpr *) expr)->collid;
+			break;
+		case T_XmlExpr:
+			if (((XmlExpr *) expr)->op == IS_XMLSERIALIZE)
+				coll = DEFAULT_COLLATION_OID;
+			else
+				coll = InvalidOid;
+			break;
+		case T_NullIfExpr:
+			coll = exprCollation((Node *) linitial(((NullIfExpr *) expr)->args));
+			break;
+		case T_NullTest:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_BooleanTest:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_CoerceToDomain:
+			coll = get_typcollation(((CoerceToDomain *) expr)->resulttype);
+			if (coll == DEFAULT_COLLATION_OID)
+				coll = exprCollation((Node *) ((CoerceToDomain *) expr)->arg);
+			break;
+		case T_CoerceToDomainValue:
+			coll = get_typcollation(((CoerceToDomainValue *) expr)->typeId);
+			break;
+		case T_SetToDefault:
+			coll = ((SetToDefault *) expr)->collid;
+			break;
+		case T_CurrentOfExpr:
+			coll = InvalidOid; /* not applicable */
+			break;
+		case T_PlaceHolderVar:
+			coll = exprCollation((Node *) ((PlaceHolderVar *) expr)->phexpr);
+			break;
+		default:
+			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
+			coll = InvalidOid;	/* keep compiler quiet */
+			break;
+	}
+
+	return coll;
+}
+
+/*
+ * Compute the result collation of a coercion-like expression that
+ * converts arg to resulttype.
+ */
+Oid
+coercion_expression_result_collation(Oid resulttype, Node *arg)
+{
+	if (type_is_collatable(resulttype))
+	{
+		if (type_is_collatable(exprType(arg)))
+			return exprCollation(arg);
+		else
+			return DEFAULT_COLLATION_OID;
+	}
+	else
+		return InvalidOid;
+}
+
 /*
  * exprIsLengthCoercion
  *		Detect whether an expression tree is an application of a datatype's
@@ -908,6 +1121,9 @@ exprLocation(Node *expr)
 				loc = leftmostLoc(loc, tc->location);
 			}
 			break;
+		case T_CollateClause:
+			loc = ((CollateClause *) expr)->location;
+			break;
 		case T_SortBy:
 			/* just use argument's location (ignore operator, if any) */
 			loc = exprLocation(((SortBy *) expr)->node);
@@ -1220,6 +1436,8 @@ expression_tree_walker(Node *node,
 			break;
 		case T_RelabelType:
 			return walker(((RelabelType *) node)->arg, context);
+		case T_CollateClause:
+			return walker(((CollateClause *) node)->arg, context);
 		case T_CoerceViaIO:
 			return walker(((CoerceViaIO *) node)->arg, context);
 		case T_ArrayCoerceExpr:
@@ -1776,6 +1994,16 @@ expression_tree_mutator(Node *node,
 				return (Node *) newnode;
 			}
 			break;
+		case T_CollateClause:
+			{
+				CollateClause *collate = (CollateClause *) node;
+				CollateClause *newnode;
+
+				FLATCOPY(newnode, collate, CollateClause);
+				MUTATE(newnode->arg, collate->arg, Expr *);
+				return (Node *) newnode;
+			}
+			break;
 		case T_CoerceViaIO:
 			{
 				CoerceViaIO *iocoerce = (CoerceViaIO *) node;
@@ -2471,6 +2699,8 @@ bool
 					return true;
 			}
 			break;
+		case T_CollateClause:
+			return walker(((CollateClause *) node)->arg, context);
 		case T_SortBy:
 			return walker(((SortBy *) node)->node, context);
 		case T_WindowDef:

src/backend/nodes/outfuncs.c

@@ -365,6 +365,10 @@ _outMergeAppend(StringInfo str, MergeAppend *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->sortOperators[i]);
 
+	appendStringInfo(str, " :collations");
+	for (i = 0; i < node->numCols; i++)
+		appendStringInfo(str, " %u", node->collations[i]);
+
 	appendStringInfo(str, " :nullsFirst");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %s", booltostr(node->nullsFirst[i]));
@@ -499,6 +503,7 @@ _outFunctionScan(StringInfo str, FunctionScan *node)
 	WRITE_NODE_FIELD(funccolnames);
 	WRITE_NODE_FIELD(funccoltypes);
 	WRITE_NODE_FIELD(funccoltypmods);
+	WRITE_NODE_FIELD(funccolcollations);
 }
 
 static void
@@ -568,6 +573,10 @@ _outMergeJoin(StringInfo str, MergeJoin *node)
 	for (i = 0; i < numCols; i++)
 		appendStringInfo(str, " %u", node->mergeFamilies[i]);
 
+	appendStringInfo(str, " :mergeCollations");
+	for (i = 0; i < numCols; i++)
+		appendStringInfo(str, " %u", node->mergeCollations[i]);
+
 	appendStringInfo(str, " :mergeStrategies");
 	for (i = 0; i < numCols; i++)
 		appendStringInfo(str, " %d", node->mergeStrategies[i]);
@@ -692,6 +701,10 @@ _outSort(StringInfo str, Sort *node)
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %u", node->sortOperators[i]);
 
+	appendStringInfo(str, " :collations");
+	for (i = 0; i < node->numCols; i++)
+		appendStringInfo(str, " %u", node->collations[i]);
+
 	appendStringInfo(str, " :nullsFirst");
 	for (i = 0; i < node->numCols; i++)
 		appendStringInfo(str, " %s", booltostr(node->nullsFirst[i]));
@@ -864,6 +877,7 @@ _outVar(StringInfo str, Var *node)
 	WRITE_INT_FIELD(varattno);
 	WRITE_OID_FIELD(vartype);
 	WRITE_INT_FIELD(vartypmod);
+	WRITE_OID_FIELD(varcollid);
 	WRITE_UINT_FIELD(varlevelsup);
 	WRITE_UINT_FIELD(varnoold);
 	WRITE_INT_FIELD(varoattno);
@@ -877,6 +891,7 @@ _outConst(StringInfo str, Const *node)
 
 	WRITE_OID_FIELD(consttype);
 	WRITE_INT_FIELD(consttypmod);
+	WRITE_OID_FIELD(constcollid);
 	WRITE_INT_FIELD(constlen);
 	WRITE_BOOL_FIELD(constbyval);
 	WRITE_BOOL_FIELD(constisnull);
@@ -898,6 +913,7 @@ _outParam(StringInfo str, Param *node)
 	WRITE_INT_FIELD(paramid);
 	WRITE_OID_FIELD(paramtype);
 	WRITE_INT_FIELD(paramtypmod);
+	WRITE_OID_FIELD(paramcollation);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -913,6 +929,7 @@ _outAggref(StringInfo str, Aggref *node)
 	WRITE_NODE_FIELD(aggdistinct);
 	WRITE_BOOL_FIELD(aggstar);
 	WRITE_UINT_FIELD(agglevelsup);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -927,6 +944,7 @@ _outWindowFunc(StringInfo str, WindowFunc *node)
 	WRITE_UINT_FIELD(winref);
 	WRITE_BOOL_FIELD(winstar);
 	WRITE_BOOL_FIELD(winagg);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -938,6 +956,7 @@ _outArrayRef(StringInfo str, ArrayRef *node)
 	WRITE_OID_FIELD(refarraytype);
 	WRITE_OID_FIELD(refelemtype);
 	WRITE_INT_FIELD(reftypmod);
+	WRITE_INT_FIELD(refcollid);
 	WRITE_NODE_FIELD(refupperindexpr);
 	WRITE_NODE_FIELD(reflowerindexpr);
 	WRITE_NODE_FIELD(refexpr);
@@ -954,6 +973,7 @@ _outFuncExpr(StringInfo str, FuncExpr *node)
 	WRITE_BOOL_FIELD(funcretset);
 	WRITE_ENUM_FIELD(funcformat, CoercionForm);
 	WRITE_NODE_FIELD(args);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -978,6 +998,7 @@ _outOpExpr(StringInfo str, OpExpr *node)
 	WRITE_OID_FIELD(opresulttype);
 	WRITE_BOOL_FIELD(opretset);
 	WRITE_NODE_FIELD(args);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -991,6 +1012,7 @@ _outDistinctExpr(StringInfo str, DistinctExpr *node)
 	WRITE_OID_FIELD(opresulttype);
 	WRITE_BOOL_FIELD(opretset);
 	WRITE_NODE_FIELD(args);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -1003,6 +1025,7 @@ _outScalarArrayOpExpr(StringInfo str, ScalarArrayOpExpr *node)
 	WRITE_OID_FIELD(opfuncid);
 	WRITE_BOOL_FIELD(useOr);
 	WRITE_NODE_FIELD(args);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -1057,6 +1080,7 @@ _outSubPlan(StringInfo str, SubPlan *node)
 	WRITE_STRING_FIELD(plan_name);
 	WRITE_OID_FIELD(firstColType);
 	WRITE_INT_FIELD(firstColTypmod);
+	WRITE_OID_FIELD(firstColCollation);
 	WRITE_BOOL_FIELD(useHashTable);
 	WRITE_BOOL_FIELD(unknownEqFalse);
 	WRITE_NODE_FIELD(setParam);
@@ -1083,6 +1107,7 @@ _outFieldSelect(StringInfo str, FieldSelect *node)
 	WRITE_INT_FIELD(fieldnum);
 	WRITE_OID_FIELD(resulttype);
 	WRITE_INT_FIELD(resulttypmod);
+	WRITE_OID_FIELD(resultcollation);
 }
 
 static void
@@ -1150,6 +1175,7 @@ _outCaseExpr(StringInfo str, CaseExpr *node)
 	WRITE_NODE_TYPE("CASE");
 
 	WRITE_OID_FIELD(casetype);
+	WRITE_OID_FIELD(casecollation);
 	WRITE_NODE_FIELD(arg);
 	WRITE_NODE_FIELD(args);
 	WRITE_NODE_FIELD(defresult);
@@ -1173,6 +1199,7 @@ _outCaseTestExpr(StringInfo str, CaseTestExpr *node)
 
 	WRITE_OID_FIELD(typeId);
 	WRITE_INT_FIELD(typeMod);
+	WRITE_OID_FIELD(collation);
 }
 
 static void
@@ -1207,6 +1234,7 @@ _outRowCompareExpr(StringInfo str, RowCompareExpr *node)
 	WRITE_ENUM_FIELD(rctype, RowCompareType);
 	WRITE_NODE_FIELD(opnos);
 	WRITE_NODE_FIELD(opfamilies);
+	WRITE_NODE_FIELD(collids);
 	WRITE_NODE_FIELD(largs);
 	WRITE_NODE_FIELD(rargs);
 }
@@ -1217,6 +1245,7 @@ _outCoalesceExpr(StringInfo str, CoalesceExpr *node)
 	WRITE_NODE_TYPE("COALESCE");
 
 	WRITE_OID_FIELD(coalescetype);
+	WRITE_OID_FIELD(coalescecollation);
 	WRITE_NODE_FIELD(args);
 	WRITE_LOCATION_FIELD(location);
 }
@@ -1229,6 +1258,7 @@ _outMinMaxExpr(StringInfo str, MinMaxExpr *node)
 	WRITE_OID_FIELD(minmaxtype);
 	WRITE_ENUM_FIELD(op, MinMaxOp);
 	WRITE_NODE_FIELD(args);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -1309,6 +1339,7 @@ _outSetToDefault(StringInfo str, SetToDefault *node)
 
 	WRITE_OID_FIELD(typeId);
 	WRITE_INT_FIELD(typeMod);
+	WRITE_OID_FIELD(collid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -1716,6 +1747,7 @@ _outPathKey(StringInfo str, PathKey *node)
 
 	WRITE_NODE_FIELD(pk_eclass);
 	WRITE_OID_FIELD(pk_opfamily);
+	WRITE_OID_FIELD(pk_collation);
 	WRITE_INT_FIELD(pk_strategy);
 	WRITE_BOOL_FIELD(pk_nulls_first);
 }
@@ -2014,6 +2046,8 @@ _outTypeName(StringInfo str, TypeName *node)
 	WRITE_NODE_FIELD(typmods);
 	WRITE_INT_FIELD(typemod);
 	WRITE_NODE_FIELD(arrayBounds);
+	WRITE_NODE_FIELD(collnames);
+	WRITE_OID_FIELD(collOid);
 	WRITE_LOCATION_FIELD(location);
 }
 
@@ -2027,6 +2061,17 @@ _outTypeCast(StringInfo str, TypeCast *node)
 	WRITE_LOCATION_FIELD(location);
 }
 
+static void
+_outCollateClause(StringInfo str, CollateClause *node)
+{
+	WRITE_NODE_TYPE("COLLATE");
+
+	WRITE_NODE_FIELD(arg);
+	WRITE_NODE_FIELD(collnames);
+	WRITE_OID_FIELD(collOid);
+	WRITE_LOCATION_FIELD(location);
+}
+
 static void
 _outIndexElem(StringInfo str, IndexElem *node)
 {
@@ -2035,6 +2080,7 @@ _outIndexElem(StringInfo str, IndexElem *node)
 	WRITE_STRING_FIELD(name);
 	WRITE_NODE_FIELD(expr);
 	WRITE_STRING_FIELD(indexcolname);
+	WRITE_NODE_FIELD(collation);
 	WRITE_NODE_FIELD(opclass);
 	WRITE_ENUM_FIELD(ordering, SortByDir);
 	WRITE_ENUM_FIELD(nulls_ordering, SortByNulls);
@@ -2162,6 +2208,7 @@ _outCommonTableExpr(StringInfo str, CommonTableExpr *node)
 	WRITE_NODE_FIELD(ctecolnames);
 	WRITE_NODE_FIELD(ctecoltypes);
 	WRITE_NODE_FIELD(ctecoltypmods);
+	WRITE_NODE_FIELD(ctecolcollations);
 }
 
 static void
@@ -2175,6 +2222,7 @@ _outSetOperationStmt(StringInfo str, SetOperationStmt *node)
 	WRITE_NODE_FIELD(rarg);
 	WRITE_NODE_FIELD(colTypes);
 	WRITE_NODE_FIELD(colTypmods);
+	WRITE_NODE_FIELD(colCollations);
 	WRITE_NODE_FIELD(groupClauses);
 }
 
@@ -2205,6 +2253,7 @@ _outRangeTblEntry(StringInfo str, RangeTblEntry *node)
 			WRITE_NODE_FIELD(funcexpr);
 			WRITE_NODE_FIELD(funccoltypes);
 			WRITE_NODE_FIELD(funccoltypmods);
+			WRITE_NODE_FIELD(funccolcollations);
 			break;
 		case RTE_VALUES:
 			WRITE_NODE_FIELD(values_lists);
@@ -2215,6 +2264,7 @@ _outRangeTblEntry(StringInfo str, RangeTblEntry *node)
 			WRITE_BOOL_FIELD(self_reference);
 			WRITE_NODE_FIELD(ctecoltypes);
 			WRITE_NODE_FIELD(ctecoltypmods);
+			WRITE_NODE_FIELD(ctecolcollations);
 			break;
 		default:
 			elog(ERROR, "unrecognized RTE kind: %d", (int) node->rtekind);
@@ -2732,6 +2782,9 @@ _outNode(StringInfo str, void *obj)
 			case T_RelabelType:
 				_outRelabelType(str, obj);
 				break;
+			case T_CollateClause:
+				_outCollateClause(str, obj);
+				break;
 			case T_CoerceViaIO:
 				_outCoerceViaIO(str, obj);
 				break;

src/backend/nodes/readfuncs.c

@@ -323,6 +323,7 @@ _readCommonTableExpr(void)
 	READ_NODE_FIELD(ctecolnames);
 	READ_NODE_FIELD(ctecoltypes);
 	READ_NODE_FIELD(ctecoltypmods);
+	READ_NODE_FIELD(ctecolcollations);
 
 	READ_DONE();
 }
@@ -341,6 +342,7 @@ _readSetOperationStmt(void)
 	READ_NODE_FIELD(rarg);
 	READ_NODE_FIELD(colTypes);
 	READ_NODE_FIELD(colTypmods);
+	READ_NODE_FIELD(colCollations);
 	READ_NODE_FIELD(groupClauses);
 
 	READ_DONE();
@@ -406,6 +408,7 @@ _readVar(void)
 	READ_INT_FIELD(varattno);
 	READ_OID_FIELD(vartype);
 	READ_INT_FIELD(vartypmod);
+	READ_OID_FIELD(varcollid);
 	READ_UINT_FIELD(varlevelsup);
 	READ_UINT_FIELD(varnoold);
 	READ_INT_FIELD(varoattno);
@@ -424,6 +427,7 @@ _readConst(void)
 
 	READ_OID_FIELD(consttype);
 	READ_INT_FIELD(consttypmod);
+	READ_OID_FIELD(constcollid);
 	READ_INT_FIELD(constlen);
 	READ_BOOL_FIELD(constbyval);
 	READ_BOOL_FIELD(constisnull);
@@ -450,6 +454,7 @@ _readParam(void)
 	READ_INT_FIELD(paramid);
 	READ_OID_FIELD(paramtype);
 	READ_INT_FIELD(paramtypmod);
+	READ_OID_FIELD(paramcollation);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -470,6 +475,7 @@ _readAggref(void)
 	READ_NODE_FIELD(aggdistinct);
 	READ_BOOL_FIELD(aggstar);
 	READ_UINT_FIELD(agglevelsup);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -489,6 +495,7 @@ _readWindowFunc(void)
 	READ_UINT_FIELD(winref);
 	READ_BOOL_FIELD(winstar);
 	READ_BOOL_FIELD(winagg);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -505,6 +512,7 @@ _readArrayRef(void)
 	READ_OID_FIELD(refarraytype);
 	READ_OID_FIELD(refelemtype);
 	READ_INT_FIELD(reftypmod);
+	READ_INT_FIELD(refcollid);
 	READ_NODE_FIELD(refupperindexpr);
 	READ_NODE_FIELD(reflowerindexpr);
 	READ_NODE_FIELD(refexpr);
@@ -526,6 +534,7 @@ _readFuncExpr(void)
 	READ_BOOL_FIELD(funcretset);
 	READ_ENUM_FIELD(funcformat, CoercionForm);
 	READ_NODE_FIELD(args);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -571,6 +580,7 @@ _readOpExpr(void)
 	READ_OID_FIELD(opresulttype);
 	READ_BOOL_FIELD(opretset);
 	READ_NODE_FIELD(args);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -600,6 +610,7 @@ _readDistinctExpr(void)
 	READ_OID_FIELD(opresulttype);
 	READ_BOOL_FIELD(opretset);
 	READ_NODE_FIELD(args);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -628,6 +639,7 @@ _readScalarArrayOpExpr(void)
 
 	READ_BOOL_FIELD(useOr);
 	READ_NODE_FIELD(args);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -692,6 +704,7 @@ _readFieldSelect(void)
 	READ_INT_FIELD(fieldnum);
 	READ_OID_FIELD(resulttype);
 	READ_INT_FIELD(resulttypmod);
+	READ_OID_FIELD(resultcollation);
 
 	READ_DONE();
 }
@@ -729,6 +742,22 @@ _readRelabelType(void)
 	READ_DONE();
 }
 
+/*
+ * _readCollateClause
+ */
+static CollateClause *
+_readCollateClause(void)
+{
+	READ_LOCALS(CollateClause);
+
+	READ_NODE_FIELD(arg);
+	READ_NODE_FIELD(collnames);
+	READ_OID_FIELD(collOid);
+	READ_LOCATION_FIELD(location);
+
+	READ_DONE();
+}
+
 /*
  * _readCoerceViaIO
  */
@@ -789,6 +818,7 @@ _readCaseExpr(void)
 	READ_LOCALS(CaseExpr);
 
 	READ_OID_FIELD(casetype);
+	READ_OID_FIELD(casecollation);
 	READ_NODE_FIELD(arg);
 	READ_NODE_FIELD(args);
 	READ_NODE_FIELD(defresult);
@@ -822,6 +852,7 @@ _readCaseTestExpr(void)
 
 	READ_OID_FIELD(typeId);
 	READ_INT_FIELD(typeMod);
+	READ_OID_FIELD(collation);
 
 	READ_DONE();
 }
@@ -871,6 +902,7 @@ _readRowCompareExpr(void)
 	READ_ENUM_FIELD(rctype, RowCompareType);
 	READ_NODE_FIELD(opnos);
 	READ_NODE_FIELD(opfamilies);
+	READ_NODE_FIELD(collids);
 	READ_NODE_FIELD(largs);
 	READ_NODE_FIELD(rargs);
 
@@ -886,6 +918,7 @@ _readCoalesceExpr(void)
 	READ_LOCALS(CoalesceExpr);
 
 	READ_OID_FIELD(coalescetype);
+	READ_OID_FIELD(coalescecollation);
 	READ_NODE_FIELD(args);
 	READ_LOCATION_FIELD(location);
 
@@ -903,6 +936,7 @@ _readMinMaxExpr(void)
 	READ_OID_FIELD(minmaxtype);
 	READ_ENUM_FIELD(op, MinMaxOp);
 	READ_NODE_FIELD(args);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -1029,6 +1063,7 @@ _readSetToDefault(void)
 
 	READ_OID_FIELD(typeId);
 	READ_INT_FIELD(typeMod);
+	READ_OID_FIELD(collid);
 	READ_LOCATION_FIELD(location);
 
 	READ_DONE();
@@ -1150,6 +1185,7 @@ _readRangeTblEntry(void)
 			READ_NODE_FIELD(funcexpr);
 			READ_NODE_FIELD(funccoltypes);
 			READ_NODE_FIELD(funccoltypmods);
+			READ_NODE_FIELD(funccolcollations);
 			break;
 		case RTE_VALUES:
 			READ_NODE_FIELD(values_lists);
@@ -1160,6 +1196,7 @@ _readRangeTblEntry(void)
 			READ_BOOL_FIELD(self_reference);
 			READ_NODE_FIELD(ctecoltypes);
 			READ_NODE_FIELD(ctecoltypmods);
+			READ_NODE_FIELD(ctecolcollations);
 			break;
 		default:
 			elog(ERROR, "unrecognized RTE kind: %d",
@@ -1248,6 +1285,8 @@ parseNodeString(void)
 		return_value = _readFieldStore();
 	else if (MATCH("RELABELTYPE", 11))
 		return_value = _readRelabelType();
+	else if (MATCH("COLLATE", 7))
+		return_value = _readCollateClause();
 	else if (MATCH("COERCEVIAIO", 11))
 		return_value = _readCoerceViaIO();
 	else if (MATCH("ARRAYCOERCEEXPR", 15))

src/backend/optimizer/path/costsize.c

@@ -1795,6 +1795,7 @@ cost_mergejoin(MergePath *path, PlannerInfo *root, SpecialJoinInfo *sjinfo)
 		ipathkey = (PathKey *) linitial(ipathkeys);
 		/* debugging check */
 		if (opathkey->pk_opfamily != ipathkey->pk_opfamily ||
+			opathkey->pk_collation != ipathkey->pk_collation ||
 			opathkey->pk_strategy != ipathkey->pk_strategy ||
 			opathkey->pk_nulls_first != ipathkey->pk_nulls_first)
 			elog(ERROR, "left and right pathkeys do not match in mergejoin");
@@ -2045,6 +2046,7 @@ cached_scansel(PlannerInfo *root, RestrictInfo *rinfo, PathKey *pathkey)
 	{
 		cache = (MergeScanSelCache *) lfirst(lc);
 		if (cache->opfamily == pathkey->pk_opfamily &&
+			cache->collation == pathkey->pk_collation &&
 			cache->strategy == pathkey->pk_strategy &&
 			cache->nulls_first == pathkey->pk_nulls_first)
 			return cache;
@@ -2054,6 +2056,7 @@ cached_scansel(PlannerInfo *root, RestrictInfo *rinfo, PathKey *pathkey)
 	mergejoinscansel(root,
 					 (Node *) rinfo->clause,
 					 pathkey->pk_opfamily,
+					 pathkey->pk_collation,
 					 pathkey->pk_strategy,
 					 pathkey->pk_nulls_first,
 					 &leftstartsel,
@@ -2066,6 +2069,7 @@ cached_scansel(PlannerInfo *root, RestrictInfo *rinfo, PathKey *pathkey)
 
 	cache = (MergeScanSelCache *) palloc(sizeof(MergeScanSelCache));
 	cache->opfamily = pathkey->pk_opfamily;
+	cache->collation = pathkey->pk_collation;
 	cache->strategy = pathkey->pk_strategy;
 	cache->nulls_first = pathkey->pk_nulls_first;
 	cache->leftstartsel = leftstartsel;

src/backend/optimizer/path/indxpath.c

@@ -23,6 +23,7 @@
 #include "catalog/pg_opfamily.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
 #include "optimizer/pathnode.h"
@@ -99,15 +100,15 @@ static List *find_clauses_for_join(PlannerInfo *root, RelOptInfo *rel,
 					  Relids outer_relids, bool isouterjoin);
 static bool match_boolean_index_clause(Node *clause, int indexcol,
 						   IndexOptInfo *index);
-static bool match_special_index_operator(Expr *clause, Oid opfamily,
+static bool match_special_index_operator(Expr *clause, Oid idxcolcollation, Oid opfamily,
 							 bool indexkey_on_left);
 static Expr *expand_boolean_index_clause(Node *clause, int indexcol,
 							IndexOptInfo *index);
-static List *expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily);
+static List *expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily, Oid collation);
 static RestrictInfo *expand_indexqual_rowcompare(RestrictInfo *rinfo,
 							IndexOptInfo *index,
 							int indexcol);
-static List *prefix_quals(Node *leftop, Oid opfamily,
+static List *prefix_quals(Node *leftop, Oid opfamily, Oid collation,
 			 Const *prefix, Pattern_Prefix_Status pstatus);
 static List *network_prefix_quals(Node *leftop, Oid expr_op, Oid opfamily,
 					 Datum rightop);
@@ -1142,7 +1143,9 @@ group_clauses_by_indexkey(IndexOptInfo *index,
  *		   and
  *	  (2)  must contain an operator which is in the same family as the index
  *		   operator for this column, or is a "special" operator as recognized
- *		   by match_special_index_operator().
+ *		   by match_special_index_operator();
+ *         and
+ *    (3)  must match the collation of the index.
  *
  *	  Our definition of "const" is pretty liberal: we allow Vars belonging
  *	  to the caller-specified outer_relids relations (which had better not
@@ -1198,6 +1201,7 @@ match_clause_to_indexcol(IndexOptInfo *index,
 						 SaOpControl saop_control)
 {
 	Expr	   *clause = rinfo->clause;
+	Oid			collation = index->indexcollations[indexcol];
 	Oid			opfamily = index->opfamily[indexcol];
 	Node	   *leftop,
 			   *rightop;
@@ -1280,7 +1284,8 @@ match_clause_to_indexcol(IndexOptInfo *index,
 		bms_is_subset(right_relids, outer_relids) &&
 		!contain_volatile_functions(rightop))
 	{
-		if (is_indexable_operator(expr_op, opfamily, true))
+		if (is_indexable_operator(expr_op, opfamily, true) &&
+			(!collation || collation == exprCollation((Node *) clause)))
 			return true;
 
 		/*
@@ -1288,7 +1293,7 @@ match_clause_to_indexcol(IndexOptInfo *index,
 		 * is a "special" indexable operator.
 		 */
 		if (plain_op &&
-			match_special_index_operator(clause, opfamily, true))
+			match_special_index_operator(clause, collation, opfamily, true))
 			return true;
 		return false;
 	}
@@ -1298,14 +1303,15 @@ match_clause_to_indexcol(IndexOptInfo *index,
 		bms_is_subset(left_relids, outer_relids) &&
 		!contain_volatile_functions(leftop))
 	{
-		if (is_indexable_operator(expr_op, opfamily, false))
+		if (is_indexable_operator(expr_op, opfamily, false) &&
+			(!collation || collation == exprCollation((Node *) clause)))
 			return true;
 
 		/*
 		 * If we didn't find a member of the index's opfamily, see whether it
 		 * is a "special" indexable operator.
 		 */
-		if (match_special_index_operator(clause, opfamily, false))
+		if (match_special_index_operator(clause, collation, opfamily, false))
 			return true;
 		return false;
 	}
@@ -1391,6 +1397,9 @@ match_rowcompare_to_indexcol(IndexOptInfo *index,
 	else
 		return false;
 
+	if (index->indexcollations[indexcol] != linitial_oid(clause->collids))
+		return false;
+
 	/* We're good if the operator is the right type of opfamily member */
 	switch (get_op_opfamily_strategy(expr_op, opfamily))
 	{
@@ -2380,7 +2389,7 @@ match_boolean_index_clause(Node *clause,
  * Return 'true' if we can do something with it anyway.
  */
 static bool
-match_special_index_operator(Expr *clause, Oid opfamily,
+match_special_index_operator(Expr *clause, Oid idxcolcollation, Oid opfamily,
 							 bool indexkey_on_left)
 {
 	bool		isIndexable = false;
@@ -2495,7 +2504,7 @@ match_special_index_operator(Expr *clause, Oid opfamily,
 			isIndexable =
 				(opfamily == TEXT_PATTERN_BTREE_FAM_OID) ||
 				(opfamily == TEXT_BTREE_FAM_OID &&
-				 (pstatus == Pattern_Prefix_Exact || lc_collate_is_c()));
+				 (pstatus == Pattern_Prefix_Exact || lc_collate_is_c(idxcolcollation)));
 			break;
 
 		case OID_BPCHAR_LIKE_OP:
@@ -2505,7 +2514,7 @@ match_special_index_operator(Expr *clause, Oid opfamily,
 			isIndexable =
 				(opfamily == BPCHAR_PATTERN_BTREE_FAM_OID) ||
 				(opfamily == BPCHAR_BTREE_FAM_OID &&
-				 (pstatus == Pattern_Prefix_Exact || lc_collate_is_c()));
+				 (pstatus == Pattern_Prefix_Exact || lc_collate_is_c(idxcolcollation)));
 			break;
 
 		case OID_NAME_LIKE_OP:
@@ -2526,6 +2535,25 @@ match_special_index_operator(Expr *clause, Oid opfamily,
 			break;
 	}
 
+	if (!isIndexable)
+		return false;
+
+	/*
+	 * For case-insensitive matching, we also need to check that the
+	 * collations match.
+	 */
+	switch (expr_op)
+	{
+		case OID_TEXT_ICLIKE_OP:
+		case OID_TEXT_ICREGEXEQ_OP:
+		case OID_BPCHAR_ICLIKE_OP:
+		case OID_BPCHAR_ICREGEXEQ_OP:
+		case OID_NAME_ICLIKE_OP:
+		case OID_NAME_ICREGEXEQ_OP:
+			isIndexable = (idxcolcollation == exprCollation((Node *) clause));
+			break;
+	}
+
 	return isIndexable;
 }
 
@@ -2561,6 +2589,7 @@ expand_indexqual_conditions(IndexOptInfo *index, List *clausegroups)
 	{
 		List	   *clausegroup = (List *) lfirst(lc);
 		Oid			curFamily = index->opfamily[indexcol];
+		Oid			curCollation = index->indexcollations[indexcol];
 		ListCell   *lc2;
 
 		foreach(lc2, clausegroup)
@@ -2592,7 +2621,8 @@ expand_indexqual_conditions(IndexOptInfo *index, List *clausegroups)
 			{
 				resultquals = list_concat(resultquals,
 										  expand_indexqual_opclause(rinfo,
-																 curFamily));
+																	curFamily,
+																	curCollation));
 			}
 			else if (IsA(clause, ScalarArrayOpExpr))
 			{
@@ -2693,7 +2723,7 @@ expand_boolean_index_clause(Node *clause,
  * expand special cases that were accepted by match_special_index_operator().
  */
 static List *
-expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily)
+expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily, Oid collation)
 {
 	Expr	   *clause = rinfo->clause;
 
@@ -2724,7 +2754,7 @@ expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily)
 			{
 				pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like,
 											   &prefix, &rest);
-				return prefix_quals(leftop, opfamily, prefix, pstatus);
+				return prefix_quals(leftop, opfamily, collation, prefix, pstatus);
 			}
 			break;
 
@@ -2736,7 +2766,7 @@ expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily)
 				/* the right-hand const is type text for all of these */
 				pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like_IC,
 											   &prefix, &rest);
-				return prefix_quals(leftop, opfamily, prefix, pstatus);
+				return prefix_quals(leftop, opfamily, collation, prefix, pstatus);
 			}
 			break;
 
@@ -2748,7 +2778,7 @@ expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily)
 				/* the right-hand const is type text for all of these */
 				pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex,
 											   &prefix, &rest);
-				return prefix_quals(leftop, opfamily, prefix, pstatus);
+				return prefix_quals(leftop, opfamily, collation, prefix, pstatus);
 			}
 			break;
 
@@ -2760,7 +2790,7 @@ expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily)
 				/* the right-hand const is type text for all of these */
 				pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC,
 											   &prefix, &rest);
-				return prefix_quals(leftop, opfamily, prefix, pstatus);
+				return prefix_quals(leftop, opfamily, collation, prefix, pstatus);
 			}
 			break;
 
@@ -2814,6 +2844,7 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
 	ListCell   *largs_cell;
 	ListCell   *rargs_cell;
 	ListCell   *opnos_cell;
+	ListCell   *collids_cell;
 
 	/* We have to figure out (again) how the first col matches */
 	var_on_left = match_index_to_operand((Node *) linitial(clause->largs),
@@ -2845,6 +2876,7 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
 	largs_cell = lnext(list_head(clause->largs));
 	rargs_cell = lnext(list_head(clause->rargs));
 	opnos_cell = lnext(list_head(clause->opnos));
+	collids_cell = lnext(list_head(clause->collids));
 
 	while (largs_cell != NULL)
 	{
@@ -2891,6 +2923,10 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
 			!= op_strategy)
 			break;
 
+		/* Does collation match? */
+		if (lfirst_oid(collids_cell) != index->indexcollations[i])
+			break;
+
 		/* Add opfamily and datatypes to lists */
 		get_op_opfamily_properties(expr_op, index->opfamily[i], false,
 								   &op_strategy,
@@ -2974,6 +3010,8 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
 		rc->opnos = new_ops;
 		rc->opfamilies = list_truncate(list_copy(clause->opfamilies),
 									   matching_cols);
+		rc->collids = list_truncate(list_copy(clause->collids),
+									matching_cols);
 		rc->largs = list_truncate((List *) copyObject(clause->largs),
 								  matching_cols);
 		rc->rargs = list_truncate((List *) copyObject(clause->rargs),
@@ -2998,7 +3036,7 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
  * operators and operand datatypes.
  */
 static List *
-prefix_quals(Node *leftop, Oid opfamily,
+prefix_quals(Node *leftop, Oid opfamily, Oid collation,
 			 Const *prefix_const, Pattern_Prefix_Status pstatus)
 {
 	List	   *result;
@@ -3100,6 +3138,7 @@ prefix_quals(Node *leftop, Oid opfamily,
 	if (oproid == InvalidOid)
 		elog(ERROR, "no < operator for opfamily %u", opfamily);
 	fmgr_info(get_opcode(oproid), &ltproc);
+	fmgr_info_collation(collation, &ltproc);
 	greaterstr = make_greater_string(prefix_const, &ltproc);
 	if (greaterstr)
 	{

src/backend/optimizer/path/pathkeys.c

@@ -18,6 +18,7 @@
 #include "postgres.h"
 
 #include "access/skey.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
@@ -30,10 +31,10 @@
 #include "utils/lsyscache.h"
 
 
-static PathKey *makePathKey(EquivalenceClass *eclass, Oid opfamily,
+static PathKey *makePathKey(EquivalenceClass *eclass, Oid opfamily, Oid collation,
 			int strategy, bool nulls_first);
 static PathKey *make_canonical_pathkey(PlannerInfo *root,
-					   EquivalenceClass *eclass, Oid opfamily,
+					   EquivalenceClass *eclass, Oid opfamily, Oid collation,
 					   int strategy, bool nulls_first);
 static bool pathkey_is_redundant(PathKey *new_pathkey, List *pathkeys);
 static Var *find_indexkey_var(PlannerInfo *root, RelOptInfo *rel,
@@ -53,13 +54,14 @@ static bool right_merge_direction(PlannerInfo *root, PathKey *pathkey);
  * convenience routine to build the specified node.
  */
 static PathKey *
-makePathKey(EquivalenceClass *eclass, Oid opfamily,
+makePathKey(EquivalenceClass *eclass, Oid opfamily, Oid collation,
 			int strategy, bool nulls_first)
 {
 	PathKey    *pk = makeNode(PathKey);
 
 	pk->pk_eclass = eclass;
 	pk->pk_opfamily = opfamily;
+	pk->pk_collation = collation;
 	pk->pk_strategy = strategy;
 	pk->pk_nulls_first = nulls_first;
 
@@ -77,7 +79,7 @@ makePathKey(EquivalenceClass *eclass, Oid opfamily,
  */
 static PathKey *
 make_canonical_pathkey(PlannerInfo *root,
-					   EquivalenceClass *eclass, Oid opfamily,
+					   EquivalenceClass *eclass, Oid opfamily, Oid collation,
 					   int strategy, bool nulls_first)
 {
 	PathKey    *pk;
@@ -93,6 +95,7 @@ make_canonical_pathkey(PlannerInfo *root,
 		pk = (PathKey *) lfirst(lc);
 		if (eclass == pk->pk_eclass &&
 			opfamily == pk->pk_opfamily &&
+			collation == pk->pk_collation &&
 			strategy == pk->pk_strategy &&
 			nulls_first == pk->pk_nulls_first)
 			return pk;
@@ -104,7 +107,7 @@ make_canonical_pathkey(PlannerInfo *root,
 	 */
 	oldcontext = MemoryContextSwitchTo(root->planner_cxt);
 
-	pk = makePathKey(eclass, opfamily, strategy, nulls_first);
+	pk = makePathKey(eclass, opfamily, collation, strategy, nulls_first);
 	root->canon_pathkeys = lappend(root->canon_pathkeys, pk);
 
 	MemoryContextSwitchTo(oldcontext);
@@ -206,6 +209,7 @@ canonicalize_pathkeys(PlannerInfo *root, List *pathkeys)
 		cpathkey = make_canonical_pathkey(root,
 										  eclass,
 										  pathkey->pk_opfamily,
+										  pathkey->pk_collation,
 										  pathkey->pk_strategy,
 										  pathkey->pk_nulls_first);
 
@@ -247,6 +251,7 @@ make_pathkey_from_sortinfo(PlannerInfo *root,
 	Oid			equality_op;
 	List	   *opfamilies;
 	EquivalenceClass *eclass;
+	Oid			collation;
 
 	strategy = reverse_sort ? BTGreaterStrategyNumber : BTLessStrategyNumber;
 
@@ -301,12 +306,14 @@ make_pathkey_from_sortinfo(PlannerInfo *root,
 	if (!eclass)
 		return NULL;
 
+	collation = exprCollation((Node *) expr);
+
 	/* And finally we can find or create a PathKey node */
 	if (canonicalize)
-		return make_canonical_pathkey(root, eclass, opfamily,
+		return make_canonical_pathkey(root, eclass, opfamily, collation,
 									  strategy, nulls_first);
 	else
-		return makePathKey(eclass, opfamily, strategy, nulls_first);
+		return makePathKey(eclass, opfamily, collation, strategy, nulls_first);
 }
 
 /*
@@ -605,7 +612,8 @@ find_indexkey_var(PlannerInfo *root, RelOptInfo *rel, AttrNumber varattno)
 	ListCell   *temp;
 	Index		relid;
 	Oid			reloid,
-				vartypeid;
+				vartypeid,
+				varcollid;
 	int32		type_mod;
 
 	foreach(temp, rel->reltargetlist)
@@ -620,8 +628,9 @@ find_indexkey_var(PlannerInfo *root, RelOptInfo *rel, AttrNumber varattno)
 	relid = rel->relid;
 	reloid = getrelid(relid, root->parse->rtable);
 	get_atttypetypmod(reloid, varattno, &vartypeid, &type_mod);
+	varcollid = get_attcollation(reloid, varattno);
 
-	return makeVar(relid, varattno, vartypeid, type_mod, 0);
+	return makeVar(relid, varattno, vartypeid, type_mod, varcollid, 0);
 }
 
 /*
@@ -703,6 +712,7 @@ convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
 						make_canonical_pathkey(root,
 											   outer_ec,
 											   sub_pathkey->pk_opfamily,
+											   sub_pathkey->pk_collation,
 											   sub_pathkey->pk_strategy,
 											   sub_pathkey->pk_nulls_first);
 			}
@@ -805,6 +815,7 @@ convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
 					outer_pk = make_canonical_pathkey(root,
 													  outer_ec,
 													sub_pathkey->pk_opfamily,
+													sub_pathkey->pk_collation,
 													sub_pathkey->pk_strategy,
 												sub_pathkey->pk_nulls_first);
 					/* score = # of equivalence peers */
@@ -1326,6 +1337,7 @@ select_outer_pathkeys_for_merge(PlannerInfo *root,
 		pathkey = make_canonical_pathkey(root,
 										 ec,
 										 linitial_oid(ec->ec_opfamilies),
+										 DEFAULT_COLLATION_OID,
 										 BTLessStrategyNumber,
 										 false);
 		/* can't be redundant because no duplicate ECs */
@@ -1419,6 +1431,7 @@ make_inner_pathkeys_for_merge(PlannerInfo *root,
 			pathkey = make_canonical_pathkey(root,
 											 ieclass,
 											 opathkey->pk_opfamily,
+											 opathkey->pk_collation,
 											 opathkey->pk_strategy,
 											 opathkey->pk_nulls_first);
 
@@ -1539,6 +1552,7 @@ right_merge_direction(PlannerInfo *root, PathKey *pathkey)
 		PathKey    *query_pathkey = (PathKey *) lfirst(l);
 
 		if (pathkey->pk_eclass == query_pathkey->pk_eclass &&
+			pathkey->pk_collation == query_pathkey->pk_collation &&
 			pathkey->pk_opfamily == query_pathkey->pk_opfamily)
 		{
 			/*

src/backend/optimizer/plan/createplan.c

@@ -105,7 +105,7 @@ static TidScan *make_tidscan(List *qptlist, List *qpqual, Index scanrelid,
 			 List *tidquals);
 static FunctionScan *make_functionscan(List *qptlist, List *qpqual,
 				  Index scanrelid, Node *funcexpr, List *funccolnames,
-				  List *funccoltypes, List *funccoltypmods);
+				  List *funccoltypes, List *funccoltypmods, List *funccolcollations);
 static ValuesScan *make_valuesscan(List *qptlist, List *qpqual,
 				Index scanrelid, List *values_lists);
 static CteScan *make_ctescan(List *qptlist, List *qpqual,
@@ -133,12 +133,13 @@ static MergeJoin *make_mergejoin(List *tlist,
 			   List *joinclauses, List *otherclauses,
 			   List *mergeclauses,
 			   Oid *mergefamilies,
+			   Oid *mergecollations,
 			   int *mergestrategies,
 			   bool *mergenullsfirst,
 			   Plan *lefttree, Plan *righttree,
 			   JoinType jointype);
 static Sort *make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
-		  AttrNumber *sortColIdx, Oid *sortOperators, bool *nullsFirst,
+		  AttrNumber *sortColIdx, Oid *sortOperators, Oid *collations, bool *nullsFirst,
 		  double limit_tuples);
 static Plan *prepare_sort_from_pathkeys(PlannerInfo *root,
 										Plan *lefttree, List *pathkeys,
@@ -146,6 +147,7 @@ static Plan *prepare_sort_from_pathkeys(PlannerInfo *root,
 										int *p_numsortkeys,
 										AttrNumber **p_sortColIdx,
 										Oid **p_sortOperators,
+										Oid **p_collations,
 										bool **p_nullsFirst);
 static Material *make_material(Plan *lefttree);
 
@@ -671,6 +673,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 									  &node->numCols,
 									  &node->sortColIdx,
 									  &node->sortOperators,
+									  &node->collations,
 									  &node->nullsFirst);
 
 	/*
@@ -685,6 +688,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 		int			numsortkeys;
 		AttrNumber *sortColIdx;
 		Oid		   *sortOperators;
+		Oid		   *collations;
 		bool	   *nullsFirst;
 
 		/* Build the child plan */
@@ -696,6 +700,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 											 &numsortkeys,
 											 &sortColIdx,
 											 &sortOperators,
+											 &collations,
 											 &nullsFirst);
 
 		/*
@@ -710,13 +715,15 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 			elog(ERROR, "MergeAppend child's targetlist doesn't match MergeAppend");
 		Assert(memcmp(sortOperators, node->sortOperators,
 					  numsortkeys * sizeof(Oid)) == 0);
+		Assert(memcmp(collations, node->collations,
+					  numsortkeys * sizeof(Oid)) == 0);
 		Assert(memcmp(nullsFirst, node->nullsFirst,
 					  numsortkeys * sizeof(bool)) == 0);
 
 		/* Now, insert a Sort node if subplan isn't sufficiently ordered */
 		if (!pathkeys_contained_in(pathkeys, subpath->pathkeys))
 			subplan = (Plan *) make_sort(root, subplan, numsortkeys,
-										 sortColIdx, sortOperators, nullsFirst,
+										 sortColIdx, sortOperators, collations, nullsFirst,
 										 best_path->limit_tuples);
 
 		subplans = lappend(subplans, subplan);
@@ -1569,7 +1576,8 @@ create_functionscan_plan(PlannerInfo *root, Path *best_path,
 								  rte->funcexpr,
 								  rte->eref->colnames,
 								  rte->funccoltypes,
-								  rte->funccoltypmods);
+								  rte->funccoltypmods,
+								  rte->funccolcollations);
 
 	copy_path_costsize(&scan_plan->scan.plan, best_path);
 
@@ -1847,6 +1855,7 @@ create_mergejoin_plan(PlannerInfo *root,
 	List	   *innerpathkeys;
 	int			nClauses;
 	Oid		   *mergefamilies;
+	Oid		   *mergecollations;
 	int		   *mergestrategies;
 	bool	   *mergenullsfirst;
 	MergeJoin  *join_plan;
@@ -1946,6 +1955,7 @@ create_mergejoin_plan(PlannerInfo *root,
 	nClauses = list_length(mergeclauses);
 	Assert(nClauses == list_length(best_path->path_mergeclauses));
 	mergefamilies = (Oid *) palloc(nClauses * sizeof(Oid));
+	mergecollations = (Oid *) palloc(nClauses * sizeof(Oid));
 	mergestrategies = (int *) palloc(nClauses * sizeof(int));
 	mergenullsfirst = (bool *) palloc(nClauses * sizeof(bool));
 
@@ -2074,12 +2084,14 @@ create_mergejoin_plan(PlannerInfo *root,
 
 		/* pathkeys should match each other too (more debugging) */
 		if (opathkey->pk_opfamily != ipathkey->pk_opfamily ||
+			opathkey->pk_collation != ipathkey->pk_collation ||
 			opathkey->pk_strategy != ipathkey->pk_strategy ||
 			opathkey->pk_nulls_first != ipathkey->pk_nulls_first)
 			elog(ERROR, "left and right pathkeys do not match in mergejoin");
 
 		/* OK, save info for executor */
 		mergefamilies[i] = opathkey->pk_opfamily;
+		mergecollations[i] = opathkey->pk_collation;
 		mergestrategies[i] = opathkey->pk_strategy;
 		mergenullsfirst[i] = opathkey->pk_nulls_first;
 		i++;
@@ -2099,6 +2111,7 @@ create_mergejoin_plan(PlannerInfo *root,
 							   otherclauses,
 							   mergeclauses,
 							   mergefamilies,
+							   mergecollations,
 							   mergestrategies,
 							   mergenullsfirst,
 							   outer_plan,
@@ -2528,6 +2541,7 @@ fix_indexqual_operand(Node *node, IndexOptInfo *index)
 				/* Found a match */
 				result = makeVar(index->rel->relid, pos + 1,
 								 exprType(lfirst(indexpr_item)), -1,
+								 exprCollation(lfirst(indexpr_item)),
 								 0);
 				return (Node *) result;
 			}
@@ -2881,7 +2895,8 @@ make_functionscan(List *qptlist,
 				  Node *funcexpr,
 				  List *funccolnames,
 				  List *funccoltypes,
-				  List *funccoltypmods)
+				  List *funccoltypmods,
+				  List *funccolcollations)
 {
 	FunctionScan *node = makeNode(FunctionScan);
 	Plan	   *plan = &node->scan.plan;
@@ -2896,6 +2911,7 @@ make_functionscan(List *qptlist,
 	node->funccolnames = funccolnames;
 	node->funccoltypes = funccoltypes;
 	node->funccoltypmods = funccoltypmods;
+	node->funccolcollations = funccolcollations;
 
 	return node;
 }
@@ -3181,6 +3197,7 @@ make_mergejoin(List *tlist,
 			   List *otherclauses,
 			   List *mergeclauses,
 			   Oid *mergefamilies,
+			   Oid *mergecollations,
 			   int *mergestrategies,
 			   bool *mergenullsfirst,
 			   Plan *lefttree,
@@ -3197,6 +3214,7 @@ make_mergejoin(List *tlist,
 	plan->righttree = righttree;
 	node->mergeclauses = mergeclauses;
 	node->mergeFamilies = mergefamilies;
+	node->mergeCollations = mergecollations;
 	node->mergeStrategies = mergestrategies;
 	node->mergeNullsFirst = mergenullsfirst;
 	node->join.jointype = jointype;
@@ -3214,7 +3232,7 @@ make_mergejoin(List *tlist,
  */
 static Sort *
 make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
-		  AttrNumber *sortColIdx, Oid *sortOperators, bool *nullsFirst,
+		  AttrNumber *sortColIdx, Oid *sortOperators, Oid *collations, bool *nullsFirst,
 		  double limit_tuples)
 {
 	Sort	   *node = makeNode(Sort);
@@ -3238,6 +3256,7 @@ make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
 	node->numCols = numCols;
 	node->sortColIdx = sortColIdx;
 	node->sortOperators = sortOperators;
+	node->collations = collations;
 	node->nullsFirst = nullsFirst;
 
 	return node;
@@ -3253,9 +3272,9 @@ make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
  * max possible number of columns.	Return value is the new column count.
  */
 static int
-add_sort_column(AttrNumber colIdx, Oid sortOp, bool nulls_first,
+add_sort_column(AttrNumber colIdx, Oid sortOp, Oid coll, bool nulls_first,
 				int numCols, AttrNumber *sortColIdx,
-				Oid *sortOperators, bool *nullsFirst)
+				Oid *sortOperators, Oid *collations, bool *nullsFirst)
 {
 	int			i;
 
@@ -3271,7 +3290,8 @@ add_sort_column(AttrNumber colIdx, Oid sortOp, bool nulls_first,
 		 * opposite nulls direction is redundant.
 		 */
 		if (sortColIdx[i] == colIdx &&
-			sortOperators[numCols] == sortOp)
+			sortOperators[numCols] == sortOp &&
+			collations[numCols] == coll)
 		{
 			/* Already sorting by this col, so extra sort key is useless */
 			return numCols;
@@ -3281,6 +3301,7 @@ add_sort_column(AttrNumber colIdx, Oid sortOp, bool nulls_first,
 	/* Add the column */
 	sortColIdx[numCols] = colIdx;
 	sortOperators[numCols] = sortOp;
+	collations[numCols] = coll;
 	nullsFirst[numCols] = nulls_first;
 	return numCols + 1;
 }
@@ -3320,6 +3341,7 @@ prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 						   int *p_numsortkeys,
 						   AttrNumber **p_sortColIdx,
 						   Oid **p_sortOperators,
+						   Oid **p_collations,
 						   bool **p_nullsFirst)
 {
 	List	   *tlist = lefttree->targetlist;
@@ -3327,6 +3349,7 @@ prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
+	Oid		   *collations;
 	bool	   *nullsFirst;
 
 	/*
@@ -3335,6 +3358,7 @@ prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 	numsortkeys = list_length(pathkeys);
 	sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
 	sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
+	collations = (Oid *) palloc(numsortkeys * sizeof(Oid));
 	nullsFirst = (bool *) palloc(numsortkeys * sizeof(bool));
 
 	numsortkeys = 0;
@@ -3493,9 +3517,10 @@ prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 		 */
 		numsortkeys = add_sort_column(tle->resno,
 									  sortop,
+									  pathkey->pk_collation,
 									  pathkey->pk_nulls_first,
 									  numsortkeys,
-									  sortColIdx, sortOperators, nullsFirst);
+									  sortColIdx, sortOperators, collations, nullsFirst);
 	}
 
 	Assert(numsortkeys > 0);
@@ -3504,6 +3529,7 @@ prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 	*p_numsortkeys = numsortkeys;
 	*p_sortColIdx = sortColIdx;
 	*p_sortOperators = sortOperators;
+	*p_collations = collations;
 	*p_nullsFirst = nullsFirst;
 
 	return lefttree;
@@ -3525,6 +3551,7 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
+	Oid		   *collations;
 	bool	   *nullsFirst;
 
 	/* Compute sort column info, and adjust lefttree as needed */
@@ -3533,11 +3560,12 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 										  &numsortkeys,
 										  &sortColIdx,
 										  &sortOperators,
+										  &collations,
 										  &nullsFirst);
 
 	/* Now build the Sort node */
 	return make_sort(root, lefttree, numsortkeys,
-					 sortColIdx, sortOperators, nullsFirst, limit_tuples);
+					 sortColIdx, sortOperators, collations, nullsFirst, limit_tuples);
 }
 
 /*
@@ -3555,6 +3583,7 @@ make_sort_from_sortclauses(PlannerInfo *root, List *sortcls, Plan *lefttree)
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
+	Oid		   *collations;
 	bool	   *nullsFirst;
 
 	/*
@@ -3563,6 +3592,7 @@ make_sort_from_sortclauses(PlannerInfo *root, List *sortcls, Plan *lefttree)
 	numsortkeys = list_length(sortcls);
 	sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
 	sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
+	collations = (Oid *) palloc(numsortkeys * sizeof(Oid));
 	nullsFirst = (bool *) palloc(numsortkeys * sizeof(bool));
 
 	numsortkeys = 0;
@@ -3578,15 +3608,16 @@ make_sort_from_sortclauses(PlannerInfo *root, List *sortcls, Plan *lefttree)
 		 * redundantly.
 		 */
 		numsortkeys = add_sort_column(tle->resno, sortcl->sortop,
+									  exprCollation((Node *) tle->expr),
 									  sortcl->nulls_first,
 									  numsortkeys,
-									  sortColIdx, sortOperators, nullsFirst);
+									  sortColIdx, sortOperators, collations, nullsFirst);
 	}
 
 	Assert(numsortkeys > 0);
 
 	return make_sort(root, lefttree, numsortkeys,
-					 sortColIdx, sortOperators, nullsFirst, -1.0);
+					 sortColIdx, sortOperators, collations, nullsFirst, -1.0);
 }
 
 /*
@@ -3614,6 +3645,7 @@ make_sort_from_groupcols(PlannerInfo *root,
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
+	Oid		   *collations;
 	bool	   *nullsFirst;
 
 	/*
@@ -3622,6 +3654,7 @@ make_sort_from_groupcols(PlannerInfo *root,
 	numsortkeys = list_length(groupcls);
 	sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
 	sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
+	collations = (Oid *) palloc(numsortkeys * sizeof(Oid));
 	nullsFirst = (bool *) palloc(numsortkeys * sizeof(bool));
 
 	numsortkeys = 0;
@@ -3637,16 +3670,17 @@ make_sort_from_groupcols(PlannerInfo *root,
 		 * redundantly.
 		 */
 		numsortkeys = add_sort_column(tle->resno, grpcl->sortop,
+									  exprCollation((Node *) tle->expr),
 									  grpcl->nulls_first,
 									  numsortkeys,
-									  sortColIdx, sortOperators, nullsFirst);
+									  sortColIdx, sortOperators, collations, nullsFirst);
 		grpno++;
 	}
 
 	Assert(numsortkeys > 0);
 
 	return make_sort(root, lefttree, numsortkeys,
-					 sortColIdx, sortOperators, nullsFirst, -1.0);
+					 sortColIdx, sortOperators, collations, nullsFirst, -1.0);
 }
 
 static Material *

src/backend/optimizer/plan/planagg.c

@@ -561,7 +561,8 @@ make_agg_subplan(PlannerInfo *root, RelOptInfo *rel, PrivateMMAggInfo *info)
 	 */
 	info->param = SS_make_initplan_from_plan(&subroot, plan,
 											 exprType((Node *) tle->expr),
-											 -1);
+											 -1,
+											 exprCollation((Node *) tle->expr));
 
 	/*
 	 * Put the updated list of InitPlans back into the outer PlannerInfo.

src/backend/optimizer/plan/setrefs.c

@@ -213,9 +213,11 @@ set_plan_references(PlannerGlobal *glob, Plan *plan,
 		newrte->funcexpr = NULL;
 		newrte->funccoltypes = NIL;
 		newrte->funccoltypmods = NIL;
+		newrte->funccolcollations = NIL;
 		newrte->values_lists = NIL;
 		newrte->ctecoltypes = NIL;
 		newrte->ctecoltypmods = NIL;
+		newrte->ctecolcollations = NIL;
 
 		glob->finalrtable = lappend(glob->finalrtable, newrte);
 
@@ -1119,6 +1121,7 @@ set_dummy_tlist_references(Plan *plan, int rtoffset)
 						 tle->resno,
 						 exprType((Node *) oldvar),
 						 exprTypmod((Node *) oldvar),
+						 exprCollation((Node *) oldvar),
 						 0);
 		if (IsA(oldvar, Var))
 		{

src/backend/optimizer/plan/subselect.c

@@ -157,6 +157,7 @@ replace_outer_var(PlannerInfo *root, Var *var)
 	retval->paramid = i;
 	retval->paramtype = var->vartype;
 	retval->paramtypmod = var->vartypmod;
+	retval->paramcollation = var->varcollid;
 	retval->location = -1;
 
 	return retval;
@@ -185,6 +186,7 @@ assign_nestloop_param(PlannerInfo *root, Var *var)
 	retval->paramid = i;
 	retval->paramtype = var->vartype;
 	retval->paramtypmod = var->vartypmod;
+	retval->paramcollation = var->varcollid;
 	retval->location = -1;
 
 	return retval;
@@ -225,6 +227,7 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
 	retval->paramid = i;
 	retval->paramtype = agg->aggtype;
 	retval->paramtypmod = -1;
+	retval->paramcollation = agg->collid;
 	retval->location = -1;
 
 	return retval;
@@ -236,7 +239,7 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
  * This is used to allocate PARAM_EXEC slots for subplan outputs.
  */
 static Param *
-generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod)
+generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod, Oid paramcollation)
 {
 	Param	   *retval;
 	PlannerParamItem *pitem;
@@ -246,6 +249,7 @@ generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod)
 	retval->paramid = list_length(root->glob->paramlist);
 	retval->paramtype = paramtype;
 	retval->paramtypmod = paramtypmod;
+	retval->paramcollation = paramcollation;
 	retval->location = -1;
 
 	pitem = makeNode(PlannerParamItem);
@@ -270,7 +274,7 @@ SS_assign_special_param(PlannerInfo *root)
 	Param	   *param;
 
 	/* We generate a Param of datatype INTERNAL */
-	param = generate_new_param(root, INTERNALOID, -1);
+	param = generate_new_param(root, INTERNALOID, -1, InvalidOid);
 	/* ... but the caller only cares about its ID */
 	return param->paramid;
 }
@@ -278,13 +282,13 @@ SS_assign_special_param(PlannerInfo *root)
 /*
  * Get the datatype of the first column of the plan's output.
  *
- * This is stored for ARRAY_SUBLINK execution and for exprType()/exprTypmod(),
+ * This is stored for ARRAY_SUBLINK execution and for exprType()/exprTypmod()/exprCollation(),
  * which have no way to get at the plan associated with a SubPlan node.
  * We really only need the info for EXPR_SUBLINK and ARRAY_SUBLINK subplans,
  * but for consistency we save it always.
  */
 static void
-get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod)
+get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod, Oid *colcollation)
 {
 	/* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */
 	if (plan->targetlist)
@@ -296,11 +300,13 @@ get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod)
 		{
 			*coltype = exprType((Node *) tent->expr);
 			*coltypmod = exprTypmod((Node *) tent->expr);
+			*colcollation = exprCollation((Node *) tent->expr);
 			return;
 		}
 	}
 	*coltype = VOIDOID;
 	*coltypmod = -1;
+	*colcollation = InvalidOid;
 }
 
 /*
@@ -470,7 +476,7 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
 	splan->subLinkType = subLinkType;
 	splan->testexpr = NULL;
 	splan->paramIds = NIL;
-	get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod);
+	get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod, &splan->firstColCollation);
 	splan->useHashTable = false;
 	splan->unknownEqFalse = unknownEqFalse;
 	splan->setParam = NIL;
@@ -523,7 +529,7 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
 		Param	   *prm;
 
 		Assert(testexpr == NULL);
-		prm = generate_new_param(root, BOOLOID, -1);
+		prm = generate_new_param(root, BOOLOID, -1, InvalidOid);
 		splan->setParam = list_make1_int(prm->paramid);
 		isInitPlan = true;
 		result = (Node *) prm;
@@ -537,7 +543,8 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
 		Assert(testexpr == NULL);
 		prm = generate_new_param(root,
 								 exprType((Node *) te->expr),
-								 exprTypmod((Node *) te->expr));
+								 exprTypmod((Node *) te->expr),
+								 exprCollation((Node *) te->expr));
 		splan->setParam = list_make1_int(prm->paramid);
 		isInitPlan = true;
 		result = (Node *) prm;
@@ -556,7 +563,8 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
 				 format_type_be(exprType((Node *) te->expr)));
 		prm = generate_new_param(root,
 								 arraytype,
-								 exprTypmod((Node *) te->expr));
+								 exprTypmod((Node *) te->expr),
+								 exprCollation((Node *) te->expr));
 		splan->setParam = list_make1_int(prm->paramid);
 		isInitPlan = true;
 		result = (Node *) prm;
@@ -708,7 +716,8 @@ generate_subquery_params(PlannerInfo *root, List *tlist, List **paramIds)
 
 		param = generate_new_param(root,
 								   exprType((Node *) tent->expr),
-								   exprTypmod((Node *) tent->expr));
+								   exprTypmod((Node *) tent->expr),
+								   exprCollation((Node *) tent->expr));
 		result = lappend(result, param);
 		ids = lappend_int(ids, param->paramid);
 	}
@@ -964,7 +973,7 @@ SS_process_ctes(PlannerInfo *root)
 		splan->subLinkType = CTE_SUBLINK;
 		splan->testexpr = NULL;
 		splan->paramIds = NIL;
-		get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod);
+		get_first_col_type(plan, &splan->firstColType, &splan->firstColTypmod, &splan->firstColCollation);
 		splan->useHashTable = false;
 		splan->unknownEqFalse = false;
 		splan->setParam = NIL;
@@ -999,7 +1008,7 @@ SS_process_ctes(PlannerInfo *root)
 		 * Assign a param to represent the query output.  We only really care
 		 * about reserving a parameter ID number.
 		 */
-		prm = generate_new_param(root, INTERNALOID, -1);
+		prm = generate_new_param(root, INTERNALOID, -1, InvalidOid);
 		splan->setParam = list_make1_int(prm->paramid);
 
 		/*
@@ -1565,7 +1574,8 @@ convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect,
 		oc = lnext(oc);
 		param = generate_new_param(root,
 								   exprType(rightarg),
-								   exprTypmod(rightarg));
+								   exprTypmod(rightarg),
+								   exprCollation(rightarg));
 		tlist = lappend(tlist,
 						makeTargetEntry((Expr *) rightarg,
 										resno++,
@@ -2352,7 +2362,7 @@ finalize_primnode(Node *node, finalize_primnode_context *context)
  */
 Param *
 SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
-						   Oid resulttype, int32 resulttypmod)
+						   Oid resulttype, int32 resulttypmod, Oid resultcollation)
 {
 	SubPlan    *node;
 	Param	   *prm;
@@ -2388,7 +2398,7 @@ SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
 	 */
 	node = makeNode(SubPlan);
 	node->subLinkType = EXPR_SUBLINK;
-	get_first_col_type(plan, &node->firstColType, &node->firstColTypmod);
+	get_first_col_type(plan, &node->firstColType, &node->firstColTypmod, &node->firstColCollation);
 	node->plan_id = list_length(root->glob->subplans);
 
 	root->init_plans = lappend(root->init_plans, node);
@@ -2403,7 +2413,7 @@ SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
 	/*
 	 * Make a Param that will be the subplan's output.
 	 */
-	prm = generate_new_param(root, resulttype, resulttypmod);
+	prm = generate_new_param(root, resulttype, resulttypmod, resultcollation);
 	node->setParam = list_make1_int(prm->paramid);
 
 	/* Label the subplan for EXPLAIN purposes */

src/backend/optimizer/prep/prepjointree.c

@@ -445,6 +445,7 @@ inline_set_returning_functions(PlannerInfo *root)
 				rte->funcexpr = NULL;
 				rte->funccoltypes = NIL;
 				rte->funccoltypmods = NIL;
+				rte->funccolcollations = NIL;
 			}
 		}
 	}

src/backend/optimizer/prep/preptlist.c

@@ -100,6 +100,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 						  SelfItemPointerAttributeNumber,
 						  TIDOID,
 						  -1,
+						  InvalidOid,
 						  0);
 			snprintf(resname, sizeof(resname), "ctid%u", rc->rti);
 			tle = makeTargetEntry((Expr *) var,
@@ -115,6 +116,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 							  TableOidAttributeNumber,
 							  OIDOID,
 							  -1,
+							  InvalidOid,
 							  0);
 				snprintf(resname, sizeof(resname), "tableoid%u", rc->rti);
 				tle = makeTargetEntry((Expr *) var,
@@ -257,6 +259,7 @@ expand_targetlist(List *tlist, int command_type,
 			 */
 			Oid			atttype = att_tup->atttypid;
 			int32		atttypmod = att_tup->atttypmod;
+			Oid			attcollation = att_tup->attcollation;
 			Node	   *new_expr;
 
 			switch (command_type)
@@ -296,6 +299,7 @@ expand_targetlist(List *tlist, int command_type,
 													attrno,
 													atttype,
 													atttypmod,
+													attcollation,
 													0);
 					}
 					else

src/backend/optimizer/prep/prepunion.c

@@ -86,7 +86,7 @@ static List *generate_setop_tlist(List *colTypes, int flag,
 					 bool hack_constants,
 					 List *input_tlist,
 					 List *refnames_tlist);
-static List *generate_append_tlist(List *colTypes, bool flag,
+static List *generate_append_tlist(List *colTypes, List *colCollations, bool flag,
 					  List *input_plans,
 					  List *refnames_tlist);
 static List *generate_setop_grouplist(SetOperationStmt *op, List *targetlist);
@@ -348,7 +348,7 @@ generate_recursion_plan(SetOperationStmt *setOp, PlannerInfo *root,
 	/*
 	 * Generate tlist for RecursiveUnion plan node --- same as in Append cases
 	 */
-	tlist = generate_append_tlist(setOp->colTypes, false,
+	tlist = generate_append_tlist(setOp->colTypes, setOp->colCollations, false,
 								  list_make2(lplan, rplan),
 								  refnames_tlist);
 
@@ -443,7 +443,7 @@ generate_union_plan(SetOperationStmt *op, PlannerInfo *root,
 	 * concerned, but we must make it look real anyway for the benefit of the
 	 * next plan level up.
 	 */
-	tlist = generate_append_tlist(op->colTypes, false,
+	tlist = generate_append_tlist(op->colTypes, op->colCollations, false,
 								  planlist, refnames_tlist);
 
 	/*
@@ -534,7 +534,7 @@ generate_nonunion_plan(SetOperationStmt *op, PlannerInfo *root,
 	 * column is shown as a variable not a constant, else setrefs.c will get
 	 * confused.
 	 */
-	tlist = generate_append_tlist(op->colTypes, true,
+	tlist = generate_append_tlist(op->colTypes, op->colCollations, true,
 								  planlist, refnames_tlist);
 
 	/*
@@ -885,6 +885,7 @@ generate_setop_tlist(List *colTypes, int flag,
 									inputtle->resno,
 									exprType((Node *) inputtle->expr),
 									exprTypmod((Node *) inputtle->expr),
+									exprCollation((Node *) inputtle->expr),
 									0);
 		if (exprType(expr) != colType)
 		{
@@ -936,13 +937,14 @@ generate_setop_tlist(List *colTypes, int flag,
  * The Vars are always generated with varno 0.
  */
 static List *
-generate_append_tlist(List *colTypes, bool flag,
+generate_append_tlist(List *colTypes, List*colCollations, bool flag,
 					  List *input_plans,
 					  List *refnames_tlist)
 {
 	List	   *tlist = NIL;
 	int			resno = 1;
 	ListCell   *curColType;
+	ListCell   *curColCollation;
 	ListCell   *ref_tl_item;
 	int			colindex;
 	TargetEntry *tle;
@@ -997,10 +999,11 @@ generate_append_tlist(List *colTypes, bool flag,
 	 * Now we can build the tlist for the Append.
 	 */
 	colindex = 0;
-	forboth(curColType, colTypes, ref_tl_item, refnames_tlist)
+	forthree(curColType, colTypes, curColCollation, colCollations, ref_tl_item, refnames_tlist)
 	{
 		Oid			colType = lfirst_oid(curColType);
 		int32		colTypmod = colTypmods[colindex++];
+		Oid			colColl = lfirst_oid(curColCollation);
 		TargetEntry *reftle = (TargetEntry *) lfirst(ref_tl_item);
 
 		Assert(reftle->resno == resno);
@@ -1009,6 +1012,7 @@ generate_append_tlist(List *colTypes, bool flag,
 								resno,
 								colType,
 								colTypmod,
+								colColl,
 								0);
 		tle = makeTargetEntry((Expr *) expr,
 							  (AttrNumber) resno++,
@@ -1025,6 +1029,7 @@ generate_append_tlist(List *colTypes, bool flag,
 								resno,
 								INT4OID,
 								-1,
+								InvalidOid,
 								0);
 		tle = makeTargetEntry((Expr *) expr,
 							  (AttrNumber) resno++,
@@ -1344,6 +1349,7 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation,
 		char	   *attname;
 		Oid			atttypid;
 		int32		atttypmod;
+		Oid			attcollation;
 		int			new_attno;
 
 		att = old_tupdesc->attrs[old_attno];
@@ -1356,6 +1362,7 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation,
 		attname = NameStr(att->attname);
 		atttypid = att->atttypid;
 		atttypmod = att->atttypmod;
+		attcollation = att->attcollation;
 
 		/*
 		 * When we are generating the "translation list" for the parent table
@@ -1367,6 +1374,7 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation,
 										 (AttrNumber) (old_attno + 1),
 										 atttypid,
 										 atttypmod,
+										 attcollation,
 										 0));
 			continue;
 		}
@@ -1409,6 +1417,7 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation,
 									 (AttrNumber) (new_attno + 1),
 									 atttypid,
 									 atttypmod,
+									 attcollation,
 									 0));
 	}
 

src/backend/optimizer/util/clauses.c

@@ -100,7 +100,7 @@ static List *simplify_and_arguments(List *args,
 					   bool *haveNull, bool *forceFalse);
 static Node *simplify_boolean_equality(Oid opno, List *args);
 static Expr *simplify_function(Oid funcid,
-				  Oid result_type, int32 result_typmod, List **args,
+				  Oid result_type, int32 result_typmod, Oid collid, List **args,
 				  bool has_named_args,
 				  bool allow_inline,
 				  eval_const_expressions_context *context);
@@ -114,7 +114,7 @@ static List *fetch_function_defaults(HeapTuple func_tuple);
 static void recheck_cast_function_args(List *args, Oid result_type,
 						   HeapTuple func_tuple);
 static Expr *evaluate_function(Oid funcid,
-				  Oid result_type, int32 result_typmod, List *args,
+				  Oid result_type, int32 result_typmod, Oid collid, List *args,
 				  HeapTuple func_tuple,
 				  eval_const_expressions_context *context);
 static Expr *inline_function(Oid funcid, Oid result_type, List *args,
@@ -156,6 +156,7 @@ make_opclause(Oid opno, Oid opresulttype, bool opretset,
 		expr->args = list_make2(leftop, rightop);
 	else
 		expr->args = list_make1(leftop);
+	expr->collid = select_common_collation(NULL, expr->args, false);
 	expr->location = -1;
 	return (Expr *) expr;
 }
@@ -1973,7 +1974,7 @@ set_coercionform_dontcare_walker(Node *node, void *context)
  */
 static bool
 rowtype_field_matches(Oid rowtypeid, int fieldnum,
-					  Oid expectedtype, int32 expectedtypmod)
+					  Oid expectedtype, int32 expectedtypmod, Oid expectedcollation)
 {
 	TupleDesc	tupdesc;
 	Form_pg_attribute attr;
@@ -1990,7 +1991,8 @@ rowtype_field_matches(Oid rowtypeid, int fieldnum,
 	attr = tupdesc->attrs[fieldnum - 1];
 	if (attr->attisdropped ||
 		attr->atttypid != expectedtype ||
-		attr->atttypmod != expectedtypmod)
+		attr->atttypmod != expectedtypmod ||
+		attr->attcollation != expectedcollation)
 	{
 		ReleaseTupleDesc(tupdesc);
 		return false;
@@ -2121,6 +2123,7 @@ eval_const_expressions_mutator(Node *node,
 					int16		typLen;
 					bool		typByVal;
 					Datum		pval;
+					Const	   *cnst;
 
 					Assert(prm->ptype == param->paramtype);
 					get_typlenbyval(param->paramtype, &typLen, &typByVal);
@@ -2128,12 +2131,14 @@ eval_const_expressions_mutator(Node *node,
 						pval = prm->value;
 					else
 						pval = datumCopy(prm->value, typByVal, typLen);
-					return (Node *) makeConst(param->paramtype,
+					cnst = makeConst(param->paramtype,
 											  param->paramtypmod,
 											  (int) typLen,
 											  pval,
 											  prm->isnull,
 											  typByVal);
+					cnst->constcollid = param->paramcollation;
+					return (Node *) cnst;
 				}
 			}
 		}
@@ -2173,6 +2178,7 @@ eval_const_expressions_mutator(Node *node,
 		 */
 		simple = simplify_function(expr->funcid,
 								   expr->funcresulttype, exprTypmod(node),
+								   expr->collid,
 								   &args,
 								   has_named_args, true, context);
 		if (simple)				/* successfully simplified it */
@@ -2190,6 +2196,7 @@ eval_const_expressions_mutator(Node *node,
 		newexpr->funcretset = expr->funcretset;
 		newexpr->funcformat = expr->funcformat;
 		newexpr->args = args;
+		newexpr->collid = expr->collid;
 		newexpr->location = expr->location;
 		return (Node *) newexpr;
 	}
@@ -2221,6 +2228,7 @@ eval_const_expressions_mutator(Node *node,
 		 */
 		simple = simplify_function(expr->opfuncid,
 								   expr->opresulttype, -1,
+								   expr->collid,
 								   &args,
 								   false, true, context);
 		if (simple)				/* successfully simplified it */
@@ -2250,6 +2258,7 @@ eval_const_expressions_mutator(Node *node,
 		newexpr->opresulttype = expr->opresulttype;
 		newexpr->opretset = expr->opretset;
 		newexpr->args = args;
+		newexpr->collid = expr->collid;
 		newexpr->location = expr->location;
 		return (Node *) newexpr;
 	}
@@ -2314,6 +2323,7 @@ eval_const_expressions_mutator(Node *node,
 			 */
 			simple = simplify_function(expr->opfuncid,
 									   expr->opresulttype, -1,
+									   expr->collid,
 									   &args,
 									   false, false, context);
 			if (simple)			/* successfully simplified it */
@@ -2342,6 +2352,7 @@ eval_const_expressions_mutator(Node *node,
 		newexpr->opresulttype = expr->opresulttype;
 		newexpr->opretset = expr->opretset;
 		newexpr->args = args;
+		newexpr->collid = expr->collid;
 		newexpr->location = expr->location;
 		return (Node *) newexpr;
 	}
@@ -2493,7 +2504,7 @@ eval_const_expressions_mutator(Node *node,
 		getTypeInputInfo(expr->resulttype, &infunc, &intypioparam);
 
 		simple = simplify_function(outfunc,
-								   CSTRINGOID, -1,
+								   CSTRINGOID, -1, InvalidOid,
 								   &args,
 								   false, true, context);
 		if (simple)				/* successfully simplified output fn */
@@ -2510,8 +2521,11 @@ eval_const_expressions_mutator(Node *node,
 										Int32GetDatum(-1),
 										false, true));
 
+			/* preserve collation of input expression */
 			simple = simplify_function(infunc,
-									   expr->resulttype, -1,
+									   expr->resulttype,
+									   -1,
+									   exprCollation((Node *) arg),
 									   &args,
 									   false, true, context);
 			if (simple)			/* successfully simplified input fn */
@@ -2690,6 +2704,7 @@ eval_const_expressions_mutator(Node *node,
 		/* Otherwise we need a new CASE node */
 		newcase = makeNode(CaseExpr);
 		newcase->casetype = caseexpr->casetype;
+		newcase->casecollation = caseexpr->casecollation;
 		newcase->arg = (Expr *) newarg;
 		newcase->args = newargs;
 		newcase->defresult = (Expr *) defresult;
@@ -2782,6 +2797,7 @@ eval_const_expressions_mutator(Node *node,
 
 		newcoalesce = makeNode(CoalesceExpr);
 		newcoalesce->coalescetype = coalesceexpr->coalescetype;
+		newcoalesce->coalescecollation = coalesceexpr->coalescecollation;
 		newcoalesce->args = newargs;
 		newcoalesce->location = coalesceexpr->location;
 		return (Node *) newcoalesce;
@@ -2811,11 +2827,13 @@ eval_const_expressions_mutator(Node *node,
 			if (rowtype_field_matches(((Var *) arg)->vartype,
 									  fselect->fieldnum,
 									  fselect->resulttype,
-									  fselect->resulttypmod))
+									  fselect->resulttypmod,
+									  fselect->resultcollation))
 				return (Node *) makeVar(((Var *) arg)->varno,
 										fselect->fieldnum,
 										fselect->resulttype,
 										fselect->resulttypmod,
+										fselect->resultcollation,
 										((Var *) arg)->varlevelsup);
 		}
 		if (arg && IsA(arg, RowExpr))
@@ -2831,9 +2849,11 @@ eval_const_expressions_mutator(Node *node,
 				if (rowtype_field_matches(rowexpr->row_typeid,
 										  fselect->fieldnum,
 										  fselect->resulttype,
-										  fselect->resulttypmod) &&
+										  fselect->resulttypmod,
+										  fselect->resultcollation) &&
 					fselect->resulttype == exprType(fld) &&
-					fselect->resulttypmod == exprTypmod(fld))
+					fselect->resulttypmod == exprTypmod(fld) &&
+					fselect->resultcollation == exprCollation(fld))
 					return fld;
 			}
 		}
@@ -2842,6 +2862,7 @@ eval_const_expressions_mutator(Node *node,
 		newfselect->fieldnum = fselect->fieldnum;
 		newfselect->resulttype = fselect->resulttype;
 		newfselect->resulttypmod = fselect->resulttypmod;
+		newfselect->resultcollation = fselect->resultcollation;
 		return (Node *) newfselect;
 	}
 	if (IsA(node, NullTest))
@@ -3299,7 +3320,7 @@ simplify_boolean_equality(Oid opno, List *args)
  * pass-by-reference, and it may get modified even if simplification fails.
  */
 static Expr *
-simplify_function(Oid funcid, Oid result_type, int32 result_typmod,
+simplify_function(Oid funcid, Oid result_type, int32 result_typmod, Oid collid,
 				  List **args,
 				  bool has_named_args,
 				  bool allow_inline,
@@ -3330,7 +3351,7 @@ simplify_function(Oid funcid, Oid result_type, int32 result_typmod,
 	else if (((Form_pg_proc) GETSTRUCT(func_tuple))->pronargs > list_length(*args))
 		*args = add_function_defaults(*args, result_type, func_tuple, context);
 
-	newexpr = evaluate_function(funcid, result_type, result_typmod, *args,
+	newexpr = evaluate_function(funcid, result_type, result_typmod, collid, *args,
 								func_tuple, context);
 
 	if (!newexpr && allow_inline)
@@ -3581,7 +3602,8 @@ recheck_cast_function_args(List *args, Oid result_type, HeapTuple func_tuple)
  * simplify the function.
  */
 static Expr *
-evaluate_function(Oid funcid, Oid result_type, int32 result_typmod, List *args,
+evaluate_function(Oid funcid, Oid result_type, int32 result_typmod, Oid collid,
+				  List *args,
 				  HeapTuple func_tuple,
 				  eval_const_expressions_context *context)
 {
@@ -3664,6 +3686,7 @@ evaluate_function(Oid funcid, Oid result_type, int32 result_typmod, List *args,
 	newexpr->funcretset = false;
 	newexpr->funcformat = COERCE_DONTCARE;		/* doesn't matter */
 	newexpr->args = args;
+	newexpr->collid = collid;
 	newexpr->location = -1;
 
 	return evaluate_expr((Expr *) newexpr, result_type, result_typmod);

src/backend/optimizer/util/plancat.c

@@ -198,10 +198,12 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 			info->indexkeys = (int *) palloc(sizeof(int) * ncolumns);
 			info->opfamily = (Oid *) palloc(sizeof(Oid) * ncolumns);
 			info->opcintype = (Oid *) palloc(sizeof(Oid) * ncolumns);
+			info->indexcollations = (Oid *) palloc(sizeof(Oid) * ncolumns);
 
 			for (i = 0; i < ncolumns; i++)
 			{
 				info->indexkeys[i] = index->indkey.values[i];
+				info->indexcollations[i] = indexRelation->rd_indcollation[i];
 				info->opfamily[i] = indexRelation->rd_opfamily[i];
 				info->opcintype[i] = indexRelation->rd_opcintype[i];
 			}
@@ -634,6 +636,7 @@ get_relation_constraints(PlannerInfo *root,
 												  i,
 												  att->atttypid,
 												  att->atttypmod,
+												  att->attcollation,
 												  0);
 					ntest->nulltesttype = IS_NOT_NULL;
 					ntest->argisrow = type_is_rowtype(att->atttypid);
@@ -797,6 +800,7 @@ build_physical_tlist(PlannerInfo *root, RelOptInfo *rel)
 							  attrno,
 							  att_tup->atttypid,
 							  att_tup->atttypmod,
+							  att_tup->attcollation,
 							  0);
 
 				tlist = lappend(tlist,

src/backend/optimizer/util/predtest.c

@@ -912,6 +912,7 @@ arrayconst_startup_fn(Node *clause, PredIterInfo info)
 	state->constexpr.xpr.type = T_Const;
 	state->constexpr.consttype = ARR_ELEMTYPE(arrayval);
 	state->constexpr.consttypmod = -1;
+	state->constexpr.constcollid = arrayconst->constcollid;
 	state->constexpr.constlen = elmlen;
 	state->constexpr.constbyval = elmbyval;
 	lsecond(state->opexpr.args) = &state->constexpr;

src/backend/parser/analyze.c

@@ -1203,6 +1203,7 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 	ListCell   *left_tlist,
 			   *lct,
 			   *lcm,
+			   *lcc,
 			   *l;
 	List	   *targetvars,
 			   *targetnames,
@@ -1296,10 +1297,11 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 	targetnames = NIL;
 	left_tlist = list_head(leftmostQuery->targetList);
 
-	forboth(lct, sostmt->colTypes, lcm, sostmt->colTypmods)
+	forthree(lct, sostmt->colTypes, lcm, sostmt->colTypmods, lcc, sostmt->colCollations)
 	{
 		Oid			colType = lfirst_oid(lct);
 		int32		colTypmod = lfirst_int(lcm);
+		Oid			colCollation = lfirst_oid(lcc);
 		TargetEntry *lefttle = (TargetEntry *) lfirst(left_tlist);
 		char	   *colName;
 		TargetEntry *tle;
@@ -1311,6 +1313,7 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 					  lefttle->resno,
 					  colType,
 					  colTypmod,
+					  colCollation,
 					  0);
 		var->location = exprLocation((Node *) lefttle->expr);
 		tle = makeTargetEntry((Expr *) var,
@@ -1418,7 +1421,7 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
  *		Recursively transform leaves and internal nodes of a set-op tree
  *
  * In addition to returning the transformed node, we return a list of
- * expression nodes showing the type, typmod, and location (for error messages)
+ * expression nodes showing the type, typmod, collation, and location (for error messages)
  * of each output column of the set-op node.  This is used only during the
  * internal recursion of this function.  At the upper levels we use
  * SetToDefault nodes for this purpose, since they carry exactly the fields
@@ -1591,6 +1594,7 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
 		*colInfo = NIL;
 		op->colTypes = NIL;
 		op->colTypmods = NIL;
+		op->colCollations = NIL;
 		op->groupClauses = NIL;
 		forboth(lci, lcolinfo, rci, rcolinfo)
 		{
@@ -1604,6 +1608,7 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
 			SetToDefault *rescolnode;
 			Oid			rescoltype;
 			int32		rescoltypmod;
+			Oid			rescolcoll;
 
 			/* select common type, same as CASE et al */
 			rescoltype = select_common_type(pstate,
@@ -1615,6 +1620,12 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
 				rescoltypmod = lcoltypmod;
 			else
 				rescoltypmod = -1;
+			/* Select common collation.  A common collation is
+			 * required for all set operators except UNION ALL; see
+			 * SQL:2008-2 7.13 SR 15c. */
+			rescolcoll = select_common_collation(pstate,
+												 list_make2(lcolnode, rcolnode),
+												 (op->op == SETOP_UNION && op->all));
 
 			/*
 			 * Verify the coercions are actually possible.	If not, we'd fail
@@ -1643,11 +1654,13 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
 			rescolnode = makeNode(SetToDefault);
 			rescolnode->typeId = rescoltype;
 			rescolnode->typeMod = rescoltypmod;
+			rescolnode->collid = rescolcoll;
 			rescolnode->location = exprLocation(bestexpr);
 			*colInfo = lappend(*colInfo, rescolnode);
 
 			op->colTypes = lappend_oid(op->colTypes, rescoltype);
 			op->colTypmods = lappend_int(op->colTypmods, rescoltypmod);
+			op->colCollations = lappend_oid(op->colCollations, rescolcoll);
 
 			/*
 			 * For all cases except UNION ALL, identify the grouping operators

src/backend/parser/gram.y

@@ -261,6 +261,7 @@ static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_
 
 %type <list>	func_name handler_name qual_Op qual_all_Op subquery_Op
 				opt_class opt_inline_handler opt_validator validator_clause
+				opt_collate
 
 %type <range>	qualified_name OptConstrFromTable
 
@@ -394,7 +395,8 @@ static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_
 %type <list>	copy_generic_opt_list copy_generic_opt_arg_list
 %type <list>	copy_options
 
-%type <typnam>	Typename SimpleTypename ConstTypename
+%type <typnam>	Typename SimpleTypename SimpleTypenameWithoutCollation
+				ConstTypename
 				GenericType Numeric opt_float
 				Character ConstCharacter
 				CharacterWithLength CharacterWithoutLength
@@ -5323,38 +5325,45 @@ index_params:	index_elem							{ $$ = list_make1($1); }
  * expressions in parens.  For backwards-compatibility reasons, we allow
  * an expression that's just a function call to be written without parens.
  */
-index_elem:	ColId opt_class opt_asc_desc opt_nulls_order
+index_elem:	ColId opt_collate opt_class opt_asc_desc opt_nulls_order
 				{
 					$$ = makeNode(IndexElem);
 					$$->name = $1;
 					$$->expr = NULL;
 					$$->indexcolname = NULL;
-					$$->opclass = $2;
-					$$->ordering = $3;
-					$$->nulls_ordering = $4;
+					$$->collation = $2;
+					$$->opclass = $3;
+					$$->ordering = $4;
+					$$->nulls_ordering = $5;
 				}
-			| func_expr opt_class opt_asc_desc opt_nulls_order
+			| func_expr opt_collate opt_class opt_asc_desc opt_nulls_order
 				{
 					$$ = makeNode(IndexElem);
 					$$->name = NULL;
 					$$->expr = $1;
 					$$->indexcolname = NULL;
-					$$->opclass = $2;
-					$$->ordering = $3;
-					$$->nulls_ordering = $4;
+					$$->collation = $2;
+					$$->opclass = $3;
+					$$->ordering = $4;
+					$$->nulls_ordering = $5;
 				}
-			| '(' a_expr ')' opt_class opt_asc_desc opt_nulls_order
+			| '(' a_expr ')' opt_collate opt_class opt_asc_desc opt_nulls_order
 				{
 					$$ = makeNode(IndexElem);
 					$$->name = NULL;
 					$$->expr = $2;
 					$$->indexcolname = NULL;
-					$$->opclass = $4;
-					$$->ordering = $5;
-					$$->nulls_ordering = $6;
+					$$->collation = $4;
+					$$->opclass = $5;
+					$$->ordering = $6;
+					$$->nulls_ordering = $7;
 				}
 		;
 
+opt_collate: COLLATE any_name						{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 opt_class:	any_name								{ $$ = $1; }
 			| USING any_name						{ $$ = $2; }
 			| /*EMPTY*/								{ $$ = NIL; }
@@ -8776,6 +8785,13 @@ opt_array_bounds:
 		;
 
 SimpleTypename:
+			SimpleTypenameWithoutCollation opt_collate
+			{
+				$$ = $1;
+				$$->collnames = $2;
+			}
+
+SimpleTypenameWithoutCollation:
 			GenericType								{ $$ = $1; }
 			| Numeric								{ $$ = $1; }
 			| Bit									{ $$ = $1; }
@@ -9811,6 +9827,14 @@ c_expr:		columnref								{ $$ = $1; }
 					r->location = @1;
 					$$ = (Node *)r;
 				}
+			| c_expr COLLATE any_name
+				{
+					CollateClause *n = makeNode(CollateClause);
+					n->arg = (Expr *) $1;
+					n->collnames = $3;
+					n->location = @2;
+					$$ = (Node *)n;
+				}
 		;
 
 /*

src/backend/parser/parse_agg.c

@@ -723,6 +723,7 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 						Oid agg_result_type,
 						Oid transfn_oid,
 						Oid finalfn_oid,
+						Oid collation,
 						Expr **transfnexpr,
 						Expr **finalfnexpr)
 {
@@ -741,6 +742,7 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 	argp->paramid = -1;
 	argp->paramtype = agg_state_type;
 	argp->paramtypmod = -1;
+	argp->paramcollation = collation;
 	argp->location = -1;
 
 	args = list_make1(argp);
@@ -752,6 +754,7 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 		argp->paramid = -1;
 		argp->paramtype = agg_input_types[i];
 		argp->paramtypmod = -1;
+		argp->paramcollation = collation;
 		argp->location = -1;
 		args = lappend(args, argp);
 	}
@@ -759,6 +762,7 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 	*transfnexpr = (Expr *) makeFuncExpr(transfn_oid,
 										 agg_state_type,
 										 args,
+										 collation,
 										 COERCE_DONTCARE);
 
 	/* see if we have a final function */
@@ -776,11 +780,13 @@ build_aggregate_fnexprs(Oid *agg_input_types,
 	argp->paramid = -1;
 	argp->paramtype = agg_state_type;
 	argp->paramtypmod = -1;
+	argp->paramcollation = collation;
 	argp->location = -1;
 	args = list_make1(argp);
 
 	*finalfnexpr = (Expr *) makeFuncExpr(finalfn_oid,
 										 agg_result_type,
 										 args,
+										 collation,
 										 COERCE_DONTCARE);
 }

src/backend/parser/parse_clause.c

@@ -613,7 +613,8 @@ transformRangeFunction(ParseState *pstate, RangeFunction *r)
 
 		tupdesc = BuildDescFromLists(rte->eref->colnames,
 									 rte->funccoltypes,
-									 rte->funccoltypmods);
+									 rte->funccoltypmods,
+									 rte->funccolcollations);
 		CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE, false);
 	}
 
@@ -1935,6 +1936,7 @@ addTargetToSortList(ParseState *pstate, TargetEntry *tle,
 					bool resolveUnknown)
 {
 	Oid			restype = exprType((Node *) tle->expr);
+	Oid			rescollation = exprCollation((Node *) tle->expr);
 	Oid			sortop;
 	Oid			eqop;
 	bool		hashable;
@@ -2018,6 +2020,12 @@ addTargetToSortList(ParseState *pstate, TargetEntry *tle,
 			break;
 	}
 
+	if (type_is_collatable(restype) && !OidIsValid(rescollation))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("no collation was derived for the sort expression"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	cancel_parser_errposition_callback(&pcbstate);
 
 	/* avoid making duplicate sortlist entries */

src/backend/parser/parse_coerce.c

@@ -16,6 +16,7 @@
 
 #include "catalog/pg_cast.h"
 #include "catalog/pg_class.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_inherits_fn.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
@@ -216,6 +217,7 @@ coerce_type(ParseState *pstate, Node *node,
 
 		newcon->consttype = baseTypeId;
 		newcon->consttypmod = inputTypeMod;
+		newcon->constcollid = get_typcollation(newcon->consttype);
 		newcon->constlen = typeLen(targetType);
 		newcon->constbyval = typeByVal(targetType);
 		newcon->constisnull = con->constisnull;
@@ -277,6 +279,14 @@ coerce_type(ParseState *pstate, Node *node,
 		if (result)
 			return result;
 	}
+	if (IsA(node, CollateClause))
+	{
+		CollateClause *cc = (CollateClause *) node;
+
+		cc->arg = (Expr *) coerce_type(pstate, (Node *) cc->arg, inputTypeId, targetTypeId, targetTypeMod,
+									   ccontext, cformat, location);
+		return (Node *) cc;
+	}
 	pathtype = find_coercion_pathway(targetTypeId, inputTypeId, ccontext,
 									 &funcId);
 	if (pathtype != COERCION_PATH_NONE)
@@ -718,6 +728,7 @@ build_coercion_expression(Node *node,
 		FuncExpr   *fexpr;
 		List	   *args;
 		Const	   *cons;
+		Oid			collation;
 
 		Assert(OidIsValid(funcId));
 
@@ -749,7 +760,9 @@ build_coercion_expression(Node *node,
 			args = lappend(args, cons);
 		}
 
-		fexpr = makeFuncExpr(funcId, targetTypeId, args, cformat);
+		collation = coercion_expression_result_collation(targetTypeId, node);
+
+		fexpr = makeFuncExpr(funcId, targetTypeId, args, collation, cformat);
 		fexpr->location = location;
 		return (Node *) fexpr;
 	}
@@ -2081,3 +2094,120 @@ typeIsOfTypedTable(Oid reltypeId, Oid reloftypeId)
 
 	return result;
 }
+
+
+/*
+ * select_common_collation() -- determine one collation to apply for
+ * an expression node, for evaluating the expression itself or to
+ * label the result of the expression node.
+ *
+ * none_ok means that it is permitted to return "no" collation.  It is
+ * then not possible to sort the result value of whatever expression
+ * is applying this.  none_ok = true reflects the rules of SQL
+ * standard clause "Result of data type combinations", none_ok = false
+ * reflects the rules of clause "Collation determination" (in some
+ * cases invoked via "Grouping operations").
+ */
+Oid
+select_common_collation(ParseState *pstate, List *exprs, bool none_ok)
+{
+	ListCell   *lc;
+
+	/*
+	 * Check if there are any explicit collation derivations.  If so,
+	 * they must all be the same.
+	 */
+	foreach(lc, exprs)
+	{
+		Node	   *pexpr = (Node *) lfirst(lc);
+		Oid			pcoll = exprCollation(pexpr);
+		bool		pexplicit = IsA(pexpr, CollateClause);
+
+		if (pcoll && pexplicit)
+		{
+			ListCell	*lc2;
+			for_each_cell(lc2, lnext(lc))
+			{
+				Node	   *nexpr = (Node *) lfirst(lc2);
+				Oid			ncoll = exprCollation(nexpr);
+				bool		nexplicit = IsA(nexpr, CollateClause);
+
+				if (!ncoll || !nexplicit)
+					continue;
+
+				if (ncoll != pcoll)
+					ereport(ERROR,
+							(errcode(ERRCODE_COLLATION_MISMATCH),
+							 errmsg("collation mismatch between explicit collations \"%s\" and \"%s\"",
+									get_collation_name(pcoll),
+									get_collation_name(ncoll)),
+							 parser_errposition(pstate, exprLocation(nexpr))));
+			}
+
+			return pcoll;
+		}
+	}
+
+	/*
+	 * Check if there are any implicit collation derivations.
+	 */
+	foreach(lc, exprs)
+	{
+		Node	   *pexpr = (Node *) lfirst(lc);
+		Oid			pcoll = exprCollation(pexpr);
+
+		if (pcoll && pcoll != DEFAULT_COLLATION_OID)
+		{
+			ListCell	*lc2;
+			for_each_cell(lc2, lnext(lc))
+			{
+				Node	   *nexpr = (Node *) lfirst(lc2);
+				Oid			ncoll = exprCollation(nexpr);
+
+				if (!ncoll || ncoll == DEFAULT_COLLATION_OID)
+					continue;
+
+				if (ncoll != pcoll)
+				{
+					if (none_ok)
+						return InvalidOid;
+					ereport(ERROR,
+							(errcode(ERRCODE_COLLATION_MISMATCH),
+							 errmsg("collation mismatch between implicit collations \"%s\" and \"%s\"",
+									get_collation_name(pcoll),
+									get_collation_name(ncoll)),
+							 errhint("You can override the collation by applying the COLLATE clause to one or both expressions."),
+							 parser_errposition(pstate, exprLocation(nexpr))));
+				}
+			}
+
+			return pcoll;
+		}
+	}
+
+	foreach(lc, exprs)
+	{
+		Node	   *pexpr = (Node *) lfirst(lc);
+		Oid			pcoll = exprCollation(pexpr);
+
+		if (pcoll == DEFAULT_COLLATION_OID)
+		{
+			ListCell	*lc2;
+			for_each_cell(lc2, lnext(lc))
+			{
+				Node	   *nexpr = (Node *) lfirst(lc2);
+				Oid			ncoll = exprCollation(nexpr);
+
+				if (ncoll != pcoll)
+					break;
+			}
+
+			return pcoll;
+		}
+	}
+
+	/*
+	 * Else use default
+	 */
+	return InvalidOid;
+}

src/backend/parser/parse_cte.c

@@ -14,11 +14,13 @@
  */
 #include "postgres.h"
 
+#include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
 #include "parser/analyze.h"
 #include "parser/parse_cte.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
 
 
 /* Enumeration of contexts in which a self-reference is disallowed */
@@ -263,11 +265,13 @@ analyzeCTE(ParseState *pstate, CommonTableExpr *cte)
 		 */
 		ListCell   *lctlist,
 				   *lctyp,
-				   *lctypmod;
+				   *lctypmod,
+				   *lccoll;
 		int			varattno;
 
 		lctyp = list_head(cte->ctecoltypes);
 		lctypmod = list_head(cte->ctecoltypmods);
+		lccoll = list_head(cte->ctecolcollations);
 		varattno = 0;
 		foreach(lctlist, query->targetList)
 		{
@@ -278,7 +282,7 @@ analyzeCTE(ParseState *pstate, CommonTableExpr *cte)
 				continue;
 			varattno++;
 			Assert(varattno == te->resno);
-			if (lctyp == NULL || lctypmod == NULL)		/* shouldn't happen */
+			if (lctyp == NULL || lctypmod == NULL || lccoll == NULL)		/* shouldn't happen */
 				elog(ERROR, "wrong number of output columns in WITH");
 			texpr = (Node *) te->expr;
 			if (exprType(texpr) != lfirst_oid(lctyp) ||
@@ -293,10 +297,20 @@ analyzeCTE(ParseState *pstate, CommonTableExpr *cte)
 														 exprTypmod(texpr))),
 						 errhint("Cast the output of the non-recursive term to the correct type."),
 						 parser_errposition(pstate, exprLocation(texpr))));
+			if (exprCollation(texpr) != lfirst_oid(lccoll))
+				ereport(ERROR,
+						(errcode(ERRCODE_COLLATION_MISMATCH),
+						 errmsg("recursive query \"%s\" column %d has collation \"%s\" in non-recursive term but collation \"%s\" overall",
+								cte->ctename, varattno,
+								get_collation_name(lfirst_oid(lccoll)),
+								get_collation_name(exprCollation(texpr))),
+						 errhint("Use the COLLATE clause to set the collation of the non-recursive term."),
+						 parser_errposition(pstate, exprLocation(texpr))));
 			lctyp = lnext(lctyp);
 			lctypmod = lnext(lctypmod);
+			lccoll = lnext(lccoll);
 		}
-		if (lctyp != NULL || lctypmod != NULL)	/* shouldn't happen */
+		if (lctyp != NULL || lctypmod != NULL || lccoll != NULL)	/* shouldn't happen */
 			elog(ERROR, "wrong number of output columns in WITH");
 	}
 }
@@ -331,7 +345,7 @@ analyzeCTETargetList(ParseState *pstate, CommonTableExpr *cte, List *tlist)
 	 * handling.)
 	 */
 	cte->ctecolnames = copyObject(cte->aliascolnames);
-	cte->ctecoltypes = cte->ctecoltypmods = NIL;
+	cte->ctecoltypes = cte->ctecoltypmods = cte->ctecolcollations = NIL;
 	numaliases = list_length(cte->aliascolnames);
 	varattno = 0;
 	foreach(tlistitem, tlist)
@@ -339,6 +353,7 @@ analyzeCTETargetList(ParseState *pstate, CommonTableExpr *cte, List *tlist)
 		TargetEntry *te = (TargetEntry *) lfirst(tlistitem);
 		Oid			coltype;
 		int32		coltypmod;
+		Oid			colcoll;
 
 		if (te->resjunk)
 			continue;
@@ -353,6 +368,7 @@ analyzeCTETargetList(ParseState *pstate, CommonTableExpr *cte, List *tlist)
 		}
 		coltype = exprType((Node *) te->expr);
 		coltypmod = exprTypmod((Node *) te->expr);
+		colcoll = exprCollation((Node *) te->expr);
 
 		/*
 		 * If the CTE is recursive, force the exposed column type of any
@@ -366,9 +382,11 @@ analyzeCTETargetList(ParseState *pstate, CommonTableExpr *cte, List *tlist)
 		{
 			coltype = TEXTOID;
 			coltypmod = -1;		/* should be -1 already, but be sure */
+			colcoll = DEFAULT_COLLATION_OID;
 		}
 		cte->ctecoltypes = lappend_oid(cte->ctecoltypes, coltype);
 		cte->ctecoltypmods = lappend_int(cte->ctecoltypmods, coltypmod);
+		cte->ctecolcollations = lappend_oid(cte->ctecolcollations, colcoll);
 	}
 	if (varattno < numaliases)
 		ereport(ERROR,

src/backend/parser/parse_expr.c

@@ -65,6 +65,7 @@ static Node *transformWholeRowRef(ParseState *pstate, RangeTblEntry *rte,
 static Node *transformIndirection(ParseState *pstate, Node *basenode,
 					 List *indirection);
 static Node *transformTypeCast(ParseState *pstate, TypeCast *tc);
+static Node *transformCollateClause(ParseState *pstate, CollateClause *c);
 static Node *make_row_comparison_op(ParseState *pstate, List *opname,
 					   List *largs, List *rargs, int location);
 static Node *make_row_distinct_op(ParseState *pstate, List *opname,
@@ -146,6 +147,12 @@ transformExpr(ParseState *pstate, Node *expr)
 			{
 				TypeCast   *tc = (TypeCast *) expr;
 
+				if (tc->typeName->collnames)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("COLLATE clause not allowed in cast target"),
+							 parser_errposition(pstate, tc->typeName->location)));
+
 				/*
 				 * If the subject of the typecast is an ARRAY[] construct and
 				 * the target type is an array type, we invoke
@@ -185,6 +192,10 @@ transformExpr(ParseState *pstate, Node *expr)
 				break;
 			}
 
+		case T_CollateClause:
+			result = transformCollateClause(pstate, (CollateClause *) expr);
+			break;
+
 		case T_A_Expr:
 			{
 				A_Expr	   *a = (A_Expr *) expr;
@@ -423,6 +434,7 @@ transformIndirection(ParseState *pstate, Node *basenode, List *indirection)
 														   exprType(result),
 														   InvalidOid,
 														   exprTypmod(result),
+														   exprCollation(result),
 														   subscripts,
 														   NULL);
 			subscripts = NIL;
@@ -444,6 +456,7 @@ transformIndirection(ParseState *pstate, Node *basenode, List *indirection)
 												   exprType(result),
 												   InvalidOid,
 												   exprTypmod(result),
+												   exprCollation(result),
 												   subscripts,
 												   NULL);
 
@@ -1267,6 +1280,7 @@ transformCaseExpr(ParseState *pstate, CaseExpr *c)
 		placeholder = makeNode(CaseTestExpr);
 		placeholder->typeId = exprType(arg);
 		placeholder->typeMod = exprTypmod(arg);
+		placeholder->collation = exprCollation(arg);
 	}
 	else
 		placeholder = NULL;
@@ -1351,6 +1365,8 @@ transformCaseExpr(ParseState *pstate, CaseExpr *c)
 								  "CASE/WHEN");
 	}
 
+	newc->casecollation = select_common_collation(pstate, resultexprs, true);
+
 	newc->location = c->location;
 
 	return (Node *) newc;
@@ -1461,6 +1477,7 @@ transformSubLink(ParseState *pstate, SubLink *sublink)
 			param->paramid = tent->resno;
 			param->paramtype = exprType((Node *) tent->expr);
 			param->paramtypmod = exprTypmod((Node *) tent->expr);
+			param->paramcollation = exprCollation((Node *) tent->expr);
 			param->location = -1;
 
 			right_list = lappend(right_list, param);
@@ -1704,6 +1721,7 @@ transformCoalesceExpr(ParseState *pstate, CoalesceExpr *c)
 	}
 
 	newc->args = newcoercedargs;
+	newc->coalescecollation = select_common_collation(pstate, newcoercedargs, true);
 	newc->location = c->location;
 	return (Node *) newc;
 }
@@ -1728,6 +1746,7 @@ transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m)
 	}
 
 	newm->minmaxtype = select_common_type(pstate, newargs, funcname, NULL);
+	newm->collid = select_common_collation(pstate, newargs, false);
 
 	/* Convert arguments if necessary */
 	foreach(args, newargs)
@@ -2082,6 +2101,36 @@ transformTypeCast(ParseState *pstate, TypeCast *tc)
 	return result;
 }
 
+/*
+ * Handle an explicit COLLATE clause.
+ *
+ * Transform the argument, and look up the collation name.
+ */
+static Node *
+transformCollateClause(ParseState *pstate, CollateClause *c)
+{
+	CollateClause *newc;
+	Oid		argtype;
+
+	newc = makeNode(CollateClause);
+	newc->arg = (Expr *) transformExpr(pstate, (Node *) c->arg);
+
+	argtype = exprType((Node *) newc->arg);
+	/* The unknown type is not collatable, but coerce_type() takes
+	 * care of it separately, so we'll let it go here. */
+	if (!type_is_collatable(argtype) && argtype != UNKNOWNOID)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("collations are not supported by type %s",
+						format_type_be(argtype))));
+
+	newc->collOid = LookupCollation(pstate, c->collnames, c->location);
+	newc->collnames = c->collnames;
+	newc->location = c->location;
+
+	return (Node *) newc;
+}
+
 /*
  * Transform a "row compare-op row" construct
  *
@@ -2103,6 +2152,7 @@ make_row_comparison_op(ParseState *pstate, List *opname,
 	List	   *opexprs;
 	List	   *opnos;
 	List	   *opfamilies;
+	List	   *collids;
 	ListCell   *l,
 			   *r;
 	List	  **opfamily_lists;
@@ -2273,6 +2323,7 @@ make_row_comparison_op(ParseState *pstate, List *opname,
 	 * possibility that make_op inserted coercion operations.
 	 */
 	opnos = NIL;
+	collids = NIL;
 	largs = NIL;
 	rargs = NIL;
 	foreach(l, opexprs)
@@ -2280,6 +2331,7 @@ make_row_comparison_op(ParseState *pstate, List *opname,
 		OpExpr	   *cmp = (OpExpr *) lfirst(l);
 
 		opnos = lappend_oid(opnos, cmp->opno);
+		collids = lappend_oid(collids, cmp->collid);
 		largs = lappend(largs, linitial(cmp->args));
 		rargs = lappend(rargs, lsecond(cmp->args));
 	}
@@ -2288,6 +2340,7 @@ make_row_comparison_op(ParseState *pstate, List *opname,
 	rcexpr->rctype = rctype;
 	rcexpr->opnos = opnos;
 	rcexpr->opfamilies = opfamilies;
+	rcexpr->collids = collids;
 	rcexpr->largs = largs;
 	rcexpr->rargs = rargs;
 

src/backend/parser/parse_func.c

@@ -78,6 +78,7 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 	bool		retset;
 	int			nvargs;
 	FuncDetailCode fdresult;
+	Oid			funccollid;
 
 	/*
 	 * Most of the rest of the parser just assumes that functions do not have
@@ -343,6 +344,12 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 	/* perform the necessary typecasting of arguments */
 	make_fn_arguments(pstate, fargs, actual_arg_types, declared_arg_types);
 
+	/* XXX: If we knew which functions required collation information,
+	 * we could selectively set the last argument to true here. */
+	funccollid = select_common_collation(pstate, fargs, false);
+	if (!OidIsValid(funccollid))
+		funccollid = get_typcollation(rettype);
+
 	/*
 	 * If it's a variadic function call, transform the last nvargs arguments
 	 * into an array --- unless it's an "any" variadic.
@@ -383,6 +390,7 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 		funcexpr->funcretset = retset;
 		funcexpr->funcformat = COERCE_EXPLICIT_CALL;
 		funcexpr->args = fargs;
+		funcexpr->collid = funccollid;
 		funcexpr->location = location;
 
 		retval = (Node *) funcexpr;
@@ -396,6 +404,7 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 		aggref->aggtype = rettype;
 		/* args, aggorder, aggdistinct will be set by transformAggregateCall */
 		aggref->aggstar = agg_star;
+		aggref->collid = funccollid;
 		/* agglevelsup will be set by transformAggregateCall */
 		aggref->location = location;
 
@@ -453,6 +462,7 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs,
 		/* winref will be set by transformWindowFuncCall */
 		wfunc->winstar = agg_star;
 		wfunc->winagg = (fdresult == FUNCDETAIL_AGGREGATE);
+		wfunc->collid = funccollid;
 		wfunc->location = location;
 
 		/*
@@ -1303,7 +1313,7 @@ FuncNameAsType(List *funcname)
 	Oid			result;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, makeTypeNameFromNameList(funcname), NULL);
+	typtup = LookupTypeName(NULL, makeTypeNameFromNameList(funcname), NULL, NULL);
 	if (typtup == NULL)
 		return InvalidOid;
 
@@ -1380,6 +1390,7 @@ ParseComplexProjection(ParseState *pstate, char *funcname, Node *first_arg,
 			fselect->fieldnum = i + 1;
 			fselect->resulttype = att->atttypid;
 			fselect->resulttypmod = att->atttypmod;
+			fselect->resultcollation = att->attcollation;
 			return (Node *) fselect;
 		}
 	}
@@ -1489,7 +1500,7 @@ LookupTypeNameOid(const TypeName *typename)
 	Oid			result;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, typename, NULL);
+	typtup = LookupTypeName(NULL, typename, NULL, NULL);
 	if (typtup == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),

src/backend/parser/parse_node.c

@@ -189,10 +189,11 @@ make_var(ParseState *pstate, RangeTblEntry *rte, int attrno, int location)
 				sublevels_up;
 	Oid			vartypeid;
 	int32		type_mod;
+	Oid			varcollid;
 
 	vnum = RTERangeTablePosn(pstate, rte, &sublevels_up);
-	get_rte_attribute_type(rte, attrno, &vartypeid, &type_mod);
-	result = makeVar(vnum, attrno, vartypeid, type_mod, sublevels_up);
+	get_rte_attribute_type(rte, attrno, &vartypeid, &type_mod, &varcollid);
+	result = makeVar(vnum, attrno, vartypeid, type_mod, varcollid, sublevels_up);
 	result->location = location;
 	return result;
 }
@@ -269,6 +270,7 @@ transformArrayType(Oid *arrayType, int32 *arrayTypmod)
  * elementType	OID of array's element type (fetch with transformArrayType,
  *				or pass InvalidOid to do it here)
  * arrayTypMod	typmod for the array (which is also typmod for the elements)
+ * arrayColl	OID of collation of array and array's elements
  * indirection	Untransformed list of subscripts (must not be NIL)
  * assignFrom	NULL for array fetch, else transformed expression for source.
  */
@@ -278,6 +280,7 @@ transformArraySubscripts(ParseState *pstate,
 						 Oid arrayType,
 						 Oid elementType,
 						 int32 arrayTypMod,
+						 Oid arrayColl,
 						 List *indirection,
 						 Node *assignFrom)
 {
@@ -404,6 +407,7 @@ transformArraySubscripts(ParseState *pstate,
 	aref->refarraytype = arrayType;
 	aref->refelemtype = elementType;
 	aref->reftypmod = arrayTypMod;
+	aref->refcollid = arrayColl;
 	aref->refupperindexpr = upperIndexpr;
 	aref->reflowerindexpr = lowerIndexpr;
 	aref->refexpr = (Expr *) arrayBase;

src/backend/parser/parse_oper.c

@@ -782,6 +782,7 @@ make_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree,
 	List	   *args;
 	Oid			rettype;
 	OpExpr	   *result;
+	Oid			opcollid;
 
 	/* Select the operator */
 	if (rtree == NULL)
@@ -861,6 +862,12 @@ make_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree,
 	/* perform the necessary typecasting of arguments */
 	make_fn_arguments(pstate, args, actual_arg_types, declared_arg_types);
 
+	/* XXX: If we knew which functions required collation information,
+	 * we could selectively set the last argument to true here. */
+	opcollid = select_common_collation(pstate, args, false);
+	if (!OidIsValid(opcollid))
+		opcollid = get_typcollation(rettype);
+
 	/* and build the expression node */
 	result = makeNode(OpExpr);
 	result->opno = oprid(tup);
@@ -868,6 +875,7 @@ make_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree,
 	result->opresulttype = rettype;
 	result->opretset = get_func_retset(opform->oprcode);
 	result->args = args;
+	result->collid = opcollid;
 	result->location = location;
 
 	ReleaseSysCache(tup);
@@ -896,6 +904,7 @@ make_scalar_array_op(ParseState *pstate, List *opname,
 	List	   *args;
 	Oid			rettype;
 	ScalarArrayOpExpr *result;
+	Oid			opcollid;
 
 	ltypeId = exprType(ltree);
 	atypeId = exprType(rtree);
@@ -990,12 +999,19 @@ make_scalar_array_op(ParseState *pstate, List *opname,
 	/* perform the necessary typecasting of arguments */
 	make_fn_arguments(pstate, args, actual_arg_types, declared_arg_types);
 
+	/* XXX: If we knew which functions required collation information,
+	 * we could selectively set the last argument to true here. */
+	opcollid = select_common_collation(pstate, args, false);
+	if (!OidIsValid(opcollid))
+		opcollid = get_typcollation(rettype);
+
 	/* and build the expression node */
 	result = makeNode(ScalarArrayOpExpr);
 	result->opno = oprid(tup);
 	result->opfuncid = opform->oprcode;
 	result->useOr = useOr;
 	result->args = args;
+	result->collid = opcollid;
 	result->location = location;
 
 	ReleaseSysCache(tup);

src/backend/parser/parse_param.c

@@ -30,6 +30,7 @@
 #include "nodes/nodeFuncs.h"
 #include "parser/parse_param.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
 
 
 typedef struct FixedParamState
@@ -113,6 +114,7 @@ fixed_paramref_hook(ParseState *pstate, ParamRef *pref)
 	param->paramid = paramno;
 	param->paramtype = parstate->paramTypes[paramno - 1];
 	param->paramtypmod = -1;
+	param->paramcollation = get_typcollation(param->paramtype);
 	param->location = pref->location;
 
 	return (Node *) param;
@@ -165,6 +167,7 @@ variable_paramref_hook(ParseState *pstate, ParamRef *pref)
 	param->paramid = paramno;
 	param->paramtype = *pptype;
 	param->paramtypmod = -1;
+	param->paramcollation = get_typcollation(param->paramtype);
 	param->location = pref->location;
 
 	return (Node *) param;

src/backend/parser/parse_relation.c

@@ -1098,6 +1098,7 @@ addRangeTableEntryForFunction(ParseState *pstate,
 	rte->funcexpr = funcexpr;
 	rte->funccoltypes = NIL;
 	rte->funccoltypmods = NIL;
+	rte->funccolcollations = NIL;
 	rte->alias = alias;
 
 	eref = makeAlias(alias ? alias->aliasname : funcname, NIL);
@@ -1157,6 +1158,7 @@ addRangeTableEntryForFunction(ParseState *pstate,
 			char	   *attrname;
 			Oid			attrtype;
 			int32		attrtypmod;
+			Oid			attrcollation;
 
 			attrname = pstrdup(n->colname);
 			if (n->typeName->setof)
@@ -1165,10 +1167,11 @@ addRangeTableEntryForFunction(ParseState *pstate,
 						 errmsg("column \"%s\" cannot be declared SETOF",
 								attrname),
 						 parser_errposition(pstate, n->typeName->location)));
-			typenameTypeIdAndMod(pstate, n->typeName, &attrtype, &attrtypmod);
+			typenameTypeIdModColl(pstate, n->typeName, &attrtype, &attrtypmod, &attrcollation);
 			eref->colnames = lappend(eref->colnames, makeString(attrname));
 			rte->funccoltypes = lappend_oid(rte->funccoltypes, attrtype);
 			rte->funccoltypmods = lappend_int(rte->funccoltypmods, attrtypmod);
+			rte->funccolcollations = lappend_oid(rte->funccolcollations, attrcollation);
 		}
 	}
 	else
@@ -1381,6 +1384,7 @@ addRangeTableEntryForCTE(ParseState *pstate,
 
 	rte->ctecoltypes = cte->ctecoltypes;
 	rte->ctecoltypmods = cte->ctecoltypmods;
+	rte->ctecolcollations = cte->ctecolcollations;
 
 	rte->alias = alias;
 	if (alias)
@@ -1573,6 +1577,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 						varnode = makeVar(rtindex, varattno,
 										  exprType((Node *) te->expr),
 										  exprTypmod((Node *) te->expr),
+										  exprCollation((Node *) te->expr),
 										  sublevels_up);
 						varnode->location = location;
 
@@ -1612,6 +1617,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 
 						varnode = makeVar(rtindex, 1,
 										  funcrettype, -1,
+										  exprCollation(rte->funcexpr),
 										  sublevels_up);
 						varnode->location = location;
 
@@ -1626,12 +1632,14 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 					{
 						ListCell   *l1;
 						ListCell   *l2;
+						ListCell   *l3;
 						int			attnum = 0;
 
-						forboth(l1, rte->funccoltypes, l2, rte->funccoltypmods)
+						forthree(l1, rte->funccoltypes, l2, rte->funccoltypmods, l3, rte->funccolcollations)
 						{
 							Oid			attrtype = lfirst_oid(l1);
 							int32		attrtypmod = lfirst_int(l2);
+							Oid			attrcollation = lfirst_oid(l3);
 							Var		   *varnode;
 
 							attnum++;
@@ -1639,6 +1647,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 											  attnum,
 											  attrtype,
 											  attrtypmod,
+											  attrcollation,
 											  sublevels_up);
 							varnode->location = location;
 							*colvars = lappend(*colvars, varnode);
@@ -1681,6 +1690,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 						varnode = makeVar(rtindex, varattno,
 										  exprType(col),
 										  exprTypmod(col),
+										  exprCollation(col),
 										  sublevels_up);
 						varnode->location = location;
 						*colvars = lappend(*colvars, varnode);
@@ -1740,6 +1750,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 						varnode = makeVar(rtindex, varattno,
 										  exprType(avar),
 										  exprTypmod(avar),
+										  exprCollation(avar),
 										  sublevels_up);
 						varnode->location = location;
 
@@ -1753,12 +1764,14 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 				ListCell   *aliasp_item = list_head(rte->eref->colnames);
 				ListCell   *lct;
 				ListCell   *lcm;
+				ListCell   *lcc;
 
 				varattno = 0;
-				forboth(lct, rte->ctecoltypes, lcm, rte->ctecoltypmods)
+				forthree(lct, rte->ctecoltypes, lcm, rte->ctecoltypmods, lcc, rte->ctecolcollations)
 				{
 					Oid			coltype = lfirst_oid(lct);
 					int32		coltypmod = lfirst_int(lcm);
+					Oid			colcoll = lfirst_oid(lcc);
 
 					varattno++;
 
@@ -1776,7 +1789,7 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 						Var		   *varnode;
 
 						varnode = makeVar(rtindex, varattno,
-										  coltype, coltypmod,
+										  coltype, coltypmod, colcoll,
 										  sublevels_up);
 						*colvars = lappend(*colvars, varnode);
 					}
@@ -1857,7 +1870,7 @@ expandTupleDesc(TupleDesc tupdesc, Alias *eref,
 			Var		   *varnode;
 
 			varnode = makeVar(rtindex, attr->attnum,
-							  attr->atttypid, attr->atttypmod,
+							  attr->atttypid, attr->atttypmod, attr->attcollation,
 							  sublevels_up);
 			varnode->location = location;
 
@@ -1968,7 +1981,7 @@ get_rte_attribute_name(RangeTblEntry *rte, AttrNumber attnum)
  */
 void
 get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
-					   Oid *vartype, int32 *vartypmod)
+					   Oid *vartype, int32 *vartypmod, Oid *varcollid)
 {
 	switch (rte->rtekind)
 	{
@@ -1998,6 +2011,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 						   get_rel_name(rte->relid))));
 				*vartype = att_tup->atttypid;
 				*vartypmod = att_tup->atttypmod;
+				*varcollid = att_tup->attcollation;
 				ReleaseSysCache(tp);
 			}
 			break;
@@ -2012,6 +2026,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 						 rte->eref->aliasname, attnum);
 				*vartype = exprType((Node *) te->expr);
 				*vartypmod = exprTypmod((Node *) te->expr);
+				*varcollid = exprCollation((Node *) te->expr);
 			}
 			break;
 		case RTE_FUNCTION:
@@ -2053,17 +2068,20 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 										rte->eref->aliasname)));
 					*vartype = att_tup->atttypid;
 					*vartypmod = att_tup->atttypmod;
+					*varcollid = att_tup->attcollation;
 				}
 				else if (functypclass == TYPEFUNC_SCALAR)
 				{
 					/* Base data type, i.e. scalar */
 					*vartype = funcrettype;
 					*vartypmod = -1;
+					*varcollid = exprCollation(rte->funcexpr);
 				}
 				else if (functypclass == TYPEFUNC_RECORD)
 				{
 					*vartype = list_nth_oid(rte->funccoltypes, attnum - 1);
 					*vartypmod = list_nth_int(rte->funccoltypmods, attnum - 1);
+					*varcollid = list_nth_oid(rte->funccolcollations, attnum - 1);
 				}
 				else
 				{
@@ -2084,6 +2102,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 				col = (Node *) list_nth(collist, attnum - 1);
 				*vartype = exprType(col);
 				*vartypmod = exprTypmod(col);
+				*varcollid = exprCollation(col);
 			}
 			break;
 		case RTE_JOIN:
@@ -2097,6 +2116,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 				aliasvar = (Node *) list_nth(rte->joinaliasvars, attnum - 1);
 				*vartype = exprType(aliasvar);
 				*vartypmod = exprTypmod(aliasvar);
+				*varcollid = exprCollation(aliasvar);
 			}
 			break;
 		case RTE_CTE:
@@ -2105,6 +2125,7 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 				Assert(attnum > 0 && attnum <= list_length(rte->ctecoltypes));
 				*vartype = list_nth_oid(rte->ctecoltypes, attnum - 1);
 				*vartypmod = list_nth_int(rte->ctecoltypmods, attnum - 1);
+				*varcollid = list_nth_oid(rte->ctecolcollations, attnum - 1);
 			}
 			break;
 		default:

src/backend/parser/parse_target.c

@@ -374,6 +374,7 @@ transformAssignedExpr(ParseState *pstate,
 	Oid			type_id;		/* type of value provided */
 	Oid			attrtype;		/* type of target column */
 	int32		attrtypmod;
+	Oid			attrcollation;
 	Relation	rd = pstate->p_target_relation;
 
 	Assert(rd != NULL);
@@ -385,6 +386,7 @@ transformAssignedExpr(ParseState *pstate,
 				 parser_errposition(pstate, location)));
 	attrtype = attnumTypeId(rd, attrno);
 	attrtypmod = rd->rd_att->attrs[attrno - 1]->atttypmod;
+	attrcollation = rd->rd_att->attrs[attrno - 1]->attcollation;
 
 	/*
 	 * If the expression is a DEFAULT placeholder, insert the attribute's
@@ -400,6 +402,7 @@ transformAssignedExpr(ParseState *pstate,
 
 		def->typeId = attrtype;
 		def->typeMod = attrtypmod;
+		def->collid = attrcollation;
 		if (indirection)
 		{
 			if (IsA(linitial(indirection), A_Indices))
@@ -786,6 +789,7 @@ transformAssignmentSubscripts(ParseState *pstate,
 											   arrayType,
 											   elementTypeId,
 											   arrayTypMod,
+											   InvalidOid,
 											   subscripts,
 											   rhs);
 
@@ -1267,6 +1271,7 @@ ExpandRowReference(ParseState *pstate, Node *expr,
 		fselect->fieldnum = i + 1;
 		fselect->resulttype = att->atttypid;
 		fselect->resulttypmod = att->atttypmod;
+		fselect->resultcollation = att->attcollation;
 
 		if (targetlist)
 		{
@@ -1338,6 +1343,8 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
 							   exprType(varnode),
 							   exprTypmod(varnode),
 							   0);
+			TupleDescInitEntryCollation(tupleDesc, i,
+										exprCollation(varnode));
 			i++;
 		}
 		Assert(lname == NULL && lvar == NULL);	/* lists same length? */
@@ -1583,6 +1590,8 @@ FigureColnameInternal(Node *node, char **name)
 				}
 			}
 			break;
+		case T_CollateClause:
+			return FigureColnameInternal((Node *) ((CollateClause *) node)->arg, name);
 		case T_CaseExpr:
 			strength = FigureColnameInternal((Node *) ((CaseExpr *) node)->defresult,
 											 name);

src/backend/parser/parse_type.c

@@ -29,6 +29,8 @@
 
 static int32 typenameTypeMod(ParseState *pstate, const TypeName *typeName,
 				Type typ);
+static Oid typenameCollation(ParseState *pstate, const TypeName *typeName,
+				Type typ);
 
 
 /*
@@ -36,7 +38,8 @@ static int32 typenameTypeMod(ParseState *pstate, const TypeName *typeName,
  *		Given a TypeName object, lookup the pg_type syscache entry of the type.
  *		Returns NULL if no such type can be found.	If the type is found,
  *		the typmod value represented in the TypeName struct is computed and
- *		stored into *typmod_p.
+ *		stored into *typmod_p, and the collation is looked up and stored into
+ *      *colloid_p.
  *
  * NB: on success, the caller must ReleaseSysCache the type tuple when done
  * with it.
@@ -51,15 +54,18 @@ static int32 typenameTypeMod(ParseState *pstate, const TypeName *typeName,
  * found but is a shell, and there is typmod decoration, an error will be
  * thrown --- this is intentional.
  *
+ * colloid_p can also be null.
+ *
  * pstate is only used for error location info, and may be NULL.
  */
 Type
 LookupTypeName(ParseState *pstate, const TypeName *typeName,
-			   int32 *typmod_p)
+			   int32 *typmod_p, Oid *collid_p)
 {
 	Oid			typoid;
 	HeapTuple	tup;
 	int32		typmod;
+	Oid			collid;
 
 	if (typeName->names == NIL)
 	{
@@ -174,6 +180,11 @@ LookupTypeName(ParseState *pstate, const TypeName *typeName,
 	if (typmod_p)
 		*typmod_p = typmod;
 
+	collid = typenameCollation(pstate, typeName, (Type) tup);
+
+	if (collid_p)
+		*collid_p = collid;
+
 	return (Type) tup;
 }
 
@@ -185,11 +196,11 @@ LookupTypeName(ParseState *pstate, const TypeName *typeName,
  * Callers of this can therefore assume the result is a fully valid type.
  */
 Type
-typenameType(ParseState *pstate, const TypeName *typeName, int32 *typmod_p)
+typenameType(ParseState *pstate, const TypeName *typeName, int32 *typmod_p, Oid *collid_p)
 {
 	Type		tup;
 
-	tup = LookupTypeName(pstate, typeName, typmod_p);
+	tup = LookupTypeName(pstate, typeName, typmod_p, collid_p);
 	if (tup == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
@@ -217,7 +228,7 @@ typenameTypeId(ParseState *pstate, const TypeName *typeName)
 	Oid			typoid;
 	Type		tup;
 
-	tup = typenameType(pstate, typeName, NULL);
+	tup = typenameType(pstate, typeName, NULL, NULL);
 	typoid = HeapTupleGetOid(tup);
 	ReleaseSysCache(tup);
 
@@ -236,7 +247,25 @@ typenameTypeIdAndMod(ParseState *pstate, const TypeName *typeName,
 {
 	Type		tup;
 
-	tup = typenameType(pstate, typeName, typmod_p);
+	tup = typenameType(pstate, typeName, typmod_p, NULL);
+	*typeid_p = HeapTupleGetOid(tup);
+	ReleaseSysCache(tup);
+}
+
+/*
+ * typenameTypeIdModColl - given a TypeName, return the type's OID,
+ * typmod, and collation
+ *
+ * This is equivalent to typenameType, but we only hand back the type OID,
+ * typmod, and collation, not the syscache entry.
+ */
+void
+typenameTypeIdModColl(ParseState *pstate, const TypeName *typeName,
+					  Oid *typeid_p, int32 *typmod_p, Oid *collid_p)
+{
+	Type		tup;
+
+	tup = typenameType(pstate, typeName, typmod_p, collid_p);
 	*typeid_p = HeapTupleGetOid(tup);
 	ReleaseSysCache(tup);
 }
@@ -350,6 +379,62 @@ typenameTypeMod(ParseState *pstate, const TypeName *typeName, Type typ)
 	return result;
 }
 
+/*
+ * typenameCollation - given a TypeName, return the collation OID
+ *
+ * This will throw an error if the TypeName includes a collation but
+ * the data type does not support collations.
+ *
+ * The actual type OID represented by the TypeName must already have been
+ * looked up, and is passed as "typ".
+ *
+ * pstate is only used for error location info, and may be NULL.
+ */
+static Oid
+typenameCollation(ParseState *pstate, const TypeName *typeName, Type typ)
+{
+	Oid typcollation = ((Form_pg_type) GETSTRUCT(typ))->typcollation;
+
+	/* return prespecified collation OID if no collation name specified */
+	if (typeName->collnames == NIL)
+	{
+		if (typeName->collOid == InvalidOid)
+			return typcollation;
+		else
+			return typeName->collOid;
+	}
+
+	if (!OidIsValid(typcollation))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("collations are not supported by type %s",
+						format_type_be(HeapTupleGetOid(typ))),
+				 parser_errposition(pstate, typeName->location)));
+
+	return LookupCollation(pstate, typeName->collnames, typeName->location);
+}
+
+/*
+ * LookupCollation
+ *
+ * Look up collation by name, return OID, with support for error
+ * location.
+ */
+Oid
+LookupCollation(ParseState *pstate, List *collnames, int location)
+{
+	Oid			colloid;
+	ParseCallbackState pcbstate;
+
+	setup_parser_errposition_callback(&pcbstate, pstate, location);
+
+	colloid = get_collation_oid(collnames, false);
+
+	cancel_parser_errposition_callback(&pcbstate);
+
+	return colloid;
+}
+
 /*
  * appendTypeNameToBuffer
  *		Append a string representing the name of a TypeName to a StringInfo.

src/backend/parser/parse_utilcmd.c

@@ -627,7 +627,8 @@ transformInhRelation(CreateStmtContext *cxt, InhRelation *inhRelation)
 		def = makeNode(ColumnDef);
 		def->colname = pstrdup(attributeName);
 		def->typeName = makeTypeNameFromOid(attribute->atttypid,
-											attribute->atttypmod);
+											attribute->atttypmod,
+											attribute->attcollation);
 		def->inhcount = 0;
 		def->is_local = true;
 		def->is_not_null = attribute->attnotnull;
@@ -821,7 +822,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 
 	AssertArg(ofTypename);
 
-	tuple = typenameType(NULL, ofTypename, NULL);
+	tuple = typenameType(NULL, ofTypename, NULL, NULL);
 	typ = (Form_pg_type) GETSTRUCT(tuple);
 	ofTypeId = HeapTupleGetOid(tuple);
 	ofTypename->typeOid = ofTypeId;		/* cached for later */
@@ -842,7 +843,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 			continue;
 
 		n->colname = pstrdup(NameStr(attr->attname));
-		n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod);
+		n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod, attr->attcollation);
 		n->constraints = NULL;
 		n->is_local = true;
 		n->is_from_type = true;
@@ -2446,7 +2447,7 @@ transformColumnType(CreateStmtContext *cxt, ColumnDef *column)
 	/*
 	 * All we really need to do here is verify that the type is valid.
 	 */
-	Type		ctype = typenameType(cxt->pstate, column->typeName, NULL);
+	Type		ctype = typenameType(cxt->pstate, column->typeName, NULL, NULL);
 
 	ReleaseSysCache(ctype);
 }

src/backend/rewrite/rewriteHandler.c

@@ -747,6 +747,7 @@ rewriteTargetListIU(Query *parsetree, Relation target_relation,
 										attrno,
 										att_tup->atttypid,
 										att_tup->atttypmod,
+										att_tup->attcollation,
 										0);
 
 			new_tle = makeTargetEntry((Expr *) new_expr,
@@ -1127,6 +1128,7 @@ rewriteTargetListUD(Query *parsetree, RangeTblEntry *target_rte,
 					  SelfItemPointerAttributeNumber,
 					  TIDOID,
 					  -1,
+					  InvalidOid,
 					  0);
 
 		attrname = "ctid";

src/backend/tsearch/ts_locale.c

@@ -13,6 +13,7 @@
  */
 #include "postgres.h"
 
+#include "catalog/pg_collation.h"
 #include "storage/fd.h"
 #include "tsearch/ts_locale.h"
 #include "tsearch/ts_public.h"
@@ -27,11 +28,12 @@ t_isdigit(const char *ptr)
 {
 	int			clen = pg_mblen(ptr);
 	wchar_t		character[2];
+	Oid			collation = DEFAULT_COLLATION_OID; /*TODO*/
 
-	if (clen == 1 || lc_ctype_is_c())
+	if (clen == 1 || lc_ctype_is_c(collation))
 		return isdigit(TOUCHAR(ptr));
 
-	char2wchar(character, 2, ptr, clen);
+	char2wchar(character, 2, ptr, clen, collation);
 
 	return iswdigit((wint_t) character[0]);
 }
@@ -41,11 +43,12 @@ t_isspace(const char *ptr)
 {
 	int			clen = pg_mblen(ptr);
 	wchar_t		character[2];
+	Oid			collation = DEFAULT_COLLATION_OID; /*TODO*/
 
-	if (clen == 1 || lc_ctype_is_c())
+	if (clen == 1 || lc_ctype_is_c(collation))
 		return isspace(TOUCHAR(ptr));
 
-	char2wchar(character, 2, ptr, clen);
+	char2wchar(character, 2, ptr, clen, collation);
 
 	return iswspace((wint_t) character[0]);
 }
@@ -55,11 +58,12 @@ t_isalpha(const char *ptr)
 {
 	int			clen = pg_mblen(ptr);
 	wchar_t		character[2];
+	Oid			collation = DEFAULT_COLLATION_OID; /*TODO*/
 
-	if (clen == 1 || lc_ctype_is_c())
+	if (clen == 1 || lc_ctype_is_c(collation))
 		return isalpha(TOUCHAR(ptr));
 
-	char2wchar(character, 2, ptr, clen);
+	char2wchar(character, 2, ptr, clen, collation);
 
 	return iswalpha((wint_t) character[0]);
 }
@@ -69,11 +73,12 @@ t_isprint(const char *ptr)
 {
 	int			clen = pg_mblen(ptr);
 	wchar_t		character[2];
+	Oid			collation = DEFAULT_COLLATION_OID; /*TODO*/
 
-	if (clen == 1 || lc_ctype_is_c())
+	if (clen == 1 || lc_ctype_is_c(collation))
 		return isprint(TOUCHAR(ptr));
 
-	char2wchar(character, 2, ptr, clen);
+	char2wchar(character, 2, ptr, clen, collation);
 
 	return iswprint((wint_t) character[0]);
 }
@@ -238,6 +243,7 @@ char *
 lowerstr_with_len(const char *str, int len)
 {
 	char	   *out;
+	Oid			collation = DEFAULT_COLLATION_OID; /*TODO*/
 
 	if (len == 0)
 		return pstrdup("");
@@ -250,7 +256,7 @@ lowerstr_with_len(const char *str, int len)
 	 * Also, for a C locale there is no need to process as multibyte. From
 	 * backend/utils/adt/oracle_compat.c Teodor
 	 */
-	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c())
+	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c(collation))
 	{
 		wchar_t    *wstr,
 				   *wptr;
@@ -263,7 +269,7 @@ lowerstr_with_len(const char *str, int len)
 		 */
 		wptr = wstr = (wchar_t *) palloc(sizeof(wchar_t) * (len + 1));
 
-		wlen = char2wchar(wstr, len + 1, str, len);
+		wlen = char2wchar(wstr, len + 1, str, len, collation);
 		Assert(wlen <= len);
 
 		while (*wptr)
@@ -278,7 +284,7 @@ lowerstr_with_len(const char *str, int len)
 		len = pg_database_encoding_max_length() * wlen + 1;
 		out = (char *) palloc(len);
 
-		wlen = wchar2char(out, wstr, len);
+		wlen = wchar2char(out, wstr, len, collation);
 
 		pfree(wstr);
 

src/backend/tsearch/wparser_def.c

@@ -14,6 +14,7 @@
 
 #include "postgres.h"
 
+#include "catalog/pg_collation.h"
 #include "commands/defrem.h"
 #include "tsearch/ts_locale.h"
 #include "tsearch/ts_public.h"
@@ -286,6 +287,7 @@ static TParser *
 TParserInit(char *str, int len)
 {
 	TParser    *prs = (TParser *) palloc0(sizeof(TParser));
+	Oid			collation = DEFAULT_COLLATION_OID; /*TODO*/
 
 	prs->charmaxlen = pg_database_encoding_max_length();
 	prs->str = str;
@@ -299,7 +301,7 @@ TParserInit(char *str, int len)
 	if (prs->charmaxlen > 1)
 	{
 		prs->usewide = true;
-		if ( lc_ctype_is_c() )
+		if ( lc_ctype_is_c(collation) )
 		{
 			/*
 			 * char2wchar doesn't work for C-locale and
@@ -311,7 +313,7 @@ TParserInit(char *str, int len)
 		else
 		{
 			prs->wstr = (wchar_t *) palloc(sizeof(wchar_t) * (prs->lenstr + 1));
-			char2wchar(prs->wstr, prs->lenstr + 1, prs->str, prs->lenstr);
+			char2wchar(prs->wstr, prs->lenstr + 1, prs->str, prs->lenstr, collation);
 		}
 	}
 	else

src/backend/utils/adt/arrayfuncs.c

@@ -3307,6 +3307,7 @@ array_cmp(FunctionCallInfo fcinfo)
 {
 	ArrayType  *array1 = PG_GETARG_ARRAYTYPE_P(0);
 	ArrayType  *array2 = PG_GETARG_ARRAYTYPE_P(1);
+	Oid			collation = PG_GET_COLLATION();
 	int			ndims1 = ARR_NDIM(array1);
 	int			ndims2 = ARR_NDIM(array2);
 	int		   *dims1 = ARR_DIMS(array1);
@@ -3341,7 +3342,8 @@ array_cmp(FunctionCallInfo fcinfo)
 	 */
 	typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
 	if (typentry == NULL ||
-		typentry->type_id != element_type)
+		typentry->type_id != element_type ||
+		typentry->cmp_proc_finfo.fn_collation != collation)
 	{
 		typentry = lookup_type_cache(element_type,
 									 TYPECACHE_CMP_PROC_FINFO);
@@ -3351,6 +3353,7 @@ array_cmp(FunctionCallInfo fcinfo)
 			   errmsg("could not identify a comparison function for type %s",
 					  format_type_be(element_type))));
 		fcinfo->flinfo->fn_extra = (void *) typentry;
+		typentry->cmp_proc_finfo.fn_collation = collation;
 	}
 	typlen = typentry->typlen;
 	typbyval = typentry->typbyval;

src/backend/utils/adt/format_type.c

@@ -18,6 +18,7 @@
 #include <ctype.h>
 
 #include "catalog/namespace.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
@@ -28,7 +29,8 @@
 #define MAX_INT32_LEN 11
 
 static char *format_type_internal(Oid type_oid, int32 typemod,
-					 bool typemod_given, bool allow_invalid);
+					 bool typemod_given, bool allow_invalid,
+								  Oid collation_oid);
 static char *printTypmod(const char *typname, int32 typmod, Oid typmodout);
 static char *
 psnprintf(size_t len, const char *fmt,...)
@@ -67,6 +69,7 @@ format_type(PG_FUNCTION_ARGS)
 {
 	Oid			type_oid;
 	int32		typemod;
+	Oid			collation_oid;
 	char	   *result;
 
 	/* Since this function is not strict, we must test for null args */
@@ -74,13 +77,14 @@ format_type(PG_FUNCTION_ARGS)
 		PG_RETURN_NULL();
 
 	type_oid = PG_GETARG_OID(0);
+	collation_oid = PG_ARGISNULL(2) ? InvalidOid : PG_GETARG_OID(2);
 
 	if (PG_ARGISNULL(1))
-		result = format_type_internal(type_oid, -1, false, true);
+		result = format_type_internal(type_oid, -1, false, true, collation_oid);
 	else
 	{
 		typemod = PG_GETARG_INT32(1);
-		result = format_type_internal(type_oid, typemod, true, true);
+		result = format_type_internal(type_oid, typemod, true, true, collation_oid);
 	}
 
 	PG_RETURN_TEXT_P(cstring_to_text(result));
@@ -95,7 +99,7 @@ format_type(PG_FUNCTION_ARGS)
 char *
 format_type_be(Oid type_oid)
 {
-	return format_type_internal(type_oid, -1, false, false);
+	return format_type_internal(type_oid, -1, false, false, InvalidOid);
 }
 
 /*
@@ -104,14 +108,15 @@ format_type_be(Oid type_oid)
 char *
 format_type_with_typemod(Oid type_oid, int32 typemod)
 {
-	return format_type_internal(type_oid, typemod, true, false);
+	return format_type_internal(type_oid, typemod, true, false, InvalidOid);
 }
 
 
 
 static char *
 format_type_internal(Oid type_oid, int32 typemod,
-					 bool typemod_given, bool allow_invalid)
+					 bool typemod_given, bool allow_invalid,
+					 Oid collation_oid)
 {
 	bool		with_typemod = typemod_given && (typemod >= 0);
 	HeapTuple	tuple;
@@ -317,6 +322,12 @@ format_type_internal(Oid type_oid, int32 typemod,
 
 	ReleaseSysCache(tuple);
 
+	if (collation_oid && collation_oid != DEFAULT_COLLATION_OID)
+	{
+		char *collstr = generate_collation_name(collation_oid);
+		buf = psnprintf(strlen(buf) + 10 + strlen(collstr), "%s COLLATE %s", buf, collstr);
+	}
+
 	return buf;
 }
 
@@ -420,7 +431,7 @@ oidvectortypes(PG_FUNCTION_ARGS)
 	for (num = 0; num < numargs; num++)
 	{
 		char	   *typename = format_type_internal(oidArray->values[num], -1,
-													false, true);
+													false, true, InvalidOid);
 		size_t		slen = strlen(typename);
 
 		if (left < (slen + 2))

src/backend/utils/adt/formatting.c

@@ -82,6 +82,7 @@
 #include <wctype.h>
 #endif
 
+#include "catalog/pg_collation.h"
 #include "mb/pg_wchar.h"
 #include "utils/builtins.h"
 #include "utils/date.h"
@@ -953,7 +954,7 @@ static void parse_format(FormatNode *node, char *str, const KeyWord *kw,
 			 KeySuffix *suf, const int *index, int ver, NUMDesc *Num);
 
 static void DCH_to_char(FormatNode *node, bool is_interval,
-			TmToChar *in, char *out);
+			TmToChar *in, char *out, Oid collid);
 static void DCH_from_char(FormatNode *node, char *in, TmFromChar *out);
 
 #ifdef DEBUG_TO_FROM_CHAR
@@ -981,7 +982,7 @@ static char *get_last_relevant_decnum(char *num);
 static void NUM_numpart_from_char(NUMProc *Np, int id, int plen);
 static void NUM_numpart_to_char(NUMProc *Np, int id);
 static char *NUM_processor(FormatNode *node, NUMDesc *Num, char *inout, char *number,
-			  int plen, int sign, bool is_to_char);
+			  int plen, int sign, bool is_to_char, Oid collid);
 static DCHCacheEntry *DCH_cache_search(char *str);
 static DCHCacheEntry *DCH_cache_getnew(char *str);
 
@@ -1470,15 +1471,19 @@ str_numth(char *dest, char *num, int type)
  * to this function.  The result is a palloc'd, null-terminated string.
  */
 char *
-str_tolower(const char *buff, size_t nbytes)
+str_tolower(const char *buff, size_t nbytes, Oid collid)
 {
 	char	   *result;
+	pg_locale_t	mylocale = 0;
 
 	if (!buff)
 		return NULL;
 
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
 #ifdef USE_WIDE_UPPER_LOWER
-	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c())
+	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c(collid))
 	{
 		wchar_t    *workspace;
 		size_t		curr_char;
@@ -1493,16 +1498,21 @@ str_tolower(const char *buff, size_t nbytes)
 		/* Output workspace cannot have more codes than input bytes */
 		workspace = (wchar_t *) palloc((nbytes + 1) * sizeof(wchar_t));
 
-		char2wchar(workspace, nbytes + 1, buff, nbytes);
+		char2wchar(workspace, nbytes + 1, buff, nbytes, collid);
 
 		for (curr_char = 0; workspace[curr_char] != 0; curr_char++)
+#ifdef HAVE_LOCALE_T
+			if (mylocale)
+				workspace[curr_char] = towlower_l(workspace[curr_char], mylocale);
+			else
+#endif
 			workspace[curr_char] = towlower(workspace[curr_char]);
 
 		/* Make result large enough; case change might change number of bytes */
 		result_size = curr_char * pg_database_encoding_max_length() + 1;
 		result = palloc(result_size);
 
-		wchar2char(result, workspace, result_size);
+		wchar2char(result, workspace, result_size, collid);
 		pfree(workspace);
 	}
 	else
@@ -1526,15 +1536,19 @@ str_tolower(const char *buff, size_t nbytes)
  * to this function.  The result is a palloc'd, null-terminated string.
  */
 char *
-str_toupper(const char *buff, size_t nbytes)
+str_toupper(const char *buff, size_t nbytes, Oid collid)
 {
 	char	   *result;
+	pg_locale_t	mylocale = 0;
 
 	if (!buff)
 		return NULL;
 
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
 #ifdef USE_WIDE_UPPER_LOWER
-	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c())
+	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c(collid))
 	{
 		wchar_t    *workspace;
 		size_t		curr_char;
@@ -1549,16 +1563,21 @@ str_toupper(const char *buff, size_t nbytes)
 		/* Output workspace cannot have more codes than input bytes */
 		workspace = (wchar_t *) palloc((nbytes + 1) * sizeof(wchar_t));
 
-		char2wchar(workspace, nbytes + 1, buff, nbytes);
+		char2wchar(workspace, nbytes + 1, buff, nbytes, collid);
 
 		for (curr_char = 0; workspace[curr_char] != 0; curr_char++)
+#ifdef HAVE_LOCALE_T
+			if (mylocale)
+				workspace[curr_char] = towupper_l(workspace[curr_char], mylocale);
+			else
+#endif
 			workspace[curr_char] = towupper(workspace[curr_char]);
 
 		/* Make result large enough; case change might change number of bytes */
 		result_size = curr_char * pg_database_encoding_max_length() + 1;
 		result = palloc(result_size);
 
-		wchar2char(result, workspace, result_size);
+		wchar2char(result, workspace, result_size, collid);
 		pfree(workspace);
 	}
 	else
@@ -1582,16 +1601,20 @@ str_toupper(const char *buff, size_t nbytes)
  * to this function.  The result is a palloc'd, null-terminated string.
  */
 char *
-str_initcap(const char *buff, size_t nbytes)
+str_initcap(const char *buff, size_t nbytes, Oid collid)
 {
 	char	   *result;
 	int			wasalnum = false;
+	pg_locale_t	mylocale = 0;
 
 	if (!buff)
 		return NULL;
 
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
 #ifdef USE_WIDE_UPPER_LOWER
-	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c())
+	if (pg_database_encoding_max_length() > 1 && !lc_ctype_is_c(collid))
 	{
 		wchar_t    *workspace;
 		size_t		curr_char;
@@ -1606,22 +1629,35 @@ str_initcap(const char *buff, size_t nbytes)
 		/* Output workspace cannot have more codes than input bytes */
 		workspace = (wchar_t *) palloc((nbytes + 1) * sizeof(wchar_t));
 
-		char2wchar(workspace, nbytes + 1, buff, nbytes);
+		char2wchar(workspace, nbytes + 1, buff, nbytes, collid);
 
 		for (curr_char = 0; workspace[curr_char] != 0; curr_char++)
 		{
-			if (wasalnum)
-				workspace[curr_char] = towlower(workspace[curr_char]);
+#ifdef HAVE_LOCALE_T
+			if (mylocale)
+			{
+				if (wasalnum)
+					workspace[curr_char] = towlower_l(workspace[curr_char], mylocale);
+				else
+					workspace[curr_char] = towupper_l(workspace[curr_char], mylocale);
+				wasalnum = iswalnum_l(workspace[curr_char], mylocale);
+			}
 			else
-				workspace[curr_char] = towupper(workspace[curr_char]);
-			wasalnum = iswalnum(workspace[curr_char]);
+#endif
+			{
+				if (wasalnum)
+					workspace[curr_char] = towlower(workspace[curr_char]);
+				else
+					workspace[curr_char] = towupper(workspace[curr_char]);
+				wasalnum = iswalnum(workspace[curr_char]);
+			}
 		}
 
 		/* Make result large enough; case change might change number of bytes */
 		result_size = curr_char * pg_database_encoding_max_length() + 1;
 		result = palloc(result_size);
 
-		wchar2char(result, workspace, result_size);
+		wchar2char(result, workspace, result_size, collid);
 		pfree(workspace);
 	}
 	else
@@ -1647,21 +1683,21 @@ str_initcap(const char *buff, size_t nbytes)
 /* convenience routines for when the input is null-terminated */
 
 static char *
-str_tolower_z(const char *buff)
+str_tolower_z(const char *buff, Oid collid)
 {
-	return str_tolower(buff, strlen(buff));
+	return str_tolower(buff, strlen(buff), collid);
 }
 
 static char *
-str_toupper_z(const char *buff)
+str_toupper_z(const char *buff, Oid collid)
 {
-	return str_toupper(buff, strlen(buff));
+	return str_toupper(buff, strlen(buff), collid);
 }
 
 static char *
-str_initcap_z(const char *buff)
+str_initcap_z(const char *buff, Oid collid)
 {
-	return str_initcap(buff, strlen(buff));
+	return str_initcap(buff, strlen(buff), collid);
 }
 
 
@@ -2039,7 +2075,7 @@ from_char_seq_search(int *dest, char **src, char **array, int type, int max,
  * ----------
  */
 static void
-DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
+DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out, Oid collid)
 {
 	FormatNode *n;
 	char	   *s;
@@ -2151,7 +2187,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				INVALID_FOR_INTERVAL;
 				if (tmtcTzn(in))
 				{
-					char	   *p = str_tolower_z(tmtcTzn(in));
+					char	   *p = str_tolower_z(tmtcTzn(in), collid);
 
 					strcpy(s, p);
 					pfree(p);
@@ -2195,10 +2231,10 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				if (!tm->tm_mon)
 					break;
 				if (S_TM(n->suffix))
-					strcpy(s, str_toupper_z(localized_full_months[tm->tm_mon - 1]));
+					strcpy(s, str_toupper_z(localized_full_months[tm->tm_mon - 1], collid));
 				else
 					sprintf(s, "%*s", S_FM(n->suffix) ? 0 : -9,
-							str_toupper_z(months_full[tm->tm_mon - 1]));
+							str_toupper_z(months_full[tm->tm_mon - 1], collid));
 				s += strlen(s);
 				break;
 			case DCH_Month:
@@ -2206,7 +2242,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				if (!tm->tm_mon)
 					break;
 				if (S_TM(n->suffix))
-					strcpy(s, str_initcap_z(localized_full_months[tm->tm_mon - 1]));
+					strcpy(s, str_initcap_z(localized_full_months[tm->tm_mon - 1], collid));
 				else
 					sprintf(s, "%*s", S_FM(n->suffix) ? 0 : -9, months_full[tm->tm_mon - 1]);
 				s += strlen(s);
@@ -2216,7 +2252,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				if (!tm->tm_mon)
 					break;
 				if (S_TM(n->suffix))
-					strcpy(s, str_tolower_z(localized_full_months[tm->tm_mon - 1]));
+					strcpy(s, str_tolower_z(localized_full_months[tm->tm_mon - 1], collid));
 				else
 				{
 					sprintf(s, "%*s", S_FM(n->suffix) ? 0 : -9, months_full[tm->tm_mon - 1]);
@@ -2229,9 +2265,9 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				if (!tm->tm_mon)
 					break;
 				if (S_TM(n->suffix))
-					strcpy(s, str_toupper_z(localized_abbrev_months[tm->tm_mon - 1]));
+					strcpy(s, str_toupper_z(localized_abbrev_months[tm->tm_mon - 1], collid));
 				else
-					strcpy(s, str_toupper_z(months[tm->tm_mon - 1]));
+					strcpy(s, str_toupper_z(months[tm->tm_mon - 1], collid));
 				s += strlen(s);
 				break;
 			case DCH_Mon:
@@ -2239,7 +2275,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				if (!tm->tm_mon)
 					break;
 				if (S_TM(n->suffix))
-					strcpy(s, str_initcap_z(localized_abbrev_months[tm->tm_mon - 1]));
+					strcpy(s, str_initcap_z(localized_abbrev_months[tm->tm_mon - 1], collid));
 				else
 					strcpy(s, months[tm->tm_mon - 1]);
 				s += strlen(s);
@@ -2249,7 +2285,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 				if (!tm->tm_mon)
 					break;
 				if (S_TM(n->suffix))
-					strcpy(s, str_tolower_z(localized_abbrev_months[tm->tm_mon - 1]));
+					strcpy(s, str_tolower_z(localized_abbrev_months[tm->tm_mon - 1], collid));
 				else
 				{
 					strcpy(s, months[tm->tm_mon - 1]);
@@ -2266,16 +2302,16 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 			case DCH_DAY:
 				INVALID_FOR_INTERVAL;
 				if (S_TM(n->suffix))
-					strcpy(s, str_toupper_z(localized_full_days[tm->tm_wday]));
+					strcpy(s, str_toupper_z(localized_full_days[tm->tm_wday], collid));
 				else
 					sprintf(s, "%*s", S_FM(n->suffix) ? 0 : -9,
-							str_toupper_z(days[tm->tm_wday]));
+							str_toupper_z(days[tm->tm_wday], collid));
 				s += strlen(s);
 				break;
 			case DCH_Day:
 				INVALID_FOR_INTERVAL;
 				if (S_TM(n->suffix))
-					strcpy(s, str_initcap_z(localized_full_days[tm->tm_wday]));
+					strcpy(s, str_initcap_z(localized_full_days[tm->tm_wday], collid));
 				else
 					sprintf(s, "%*s", S_FM(n->suffix) ? 0 : -9, days[tm->tm_wday]);
 				s += strlen(s);
@@ -2283,7 +2319,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 			case DCH_day:
 				INVALID_FOR_INTERVAL;
 				if (S_TM(n->suffix))
-					strcpy(s, str_tolower_z(localized_full_days[tm->tm_wday]));
+					strcpy(s, str_tolower_z(localized_full_days[tm->tm_wday], collid));
 				else
 				{
 					sprintf(s, "%*s", S_FM(n->suffix) ? 0 : -9, days[tm->tm_wday]);
@@ -2294,15 +2330,15 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 			case DCH_DY:
 				INVALID_FOR_INTERVAL;
 				if (S_TM(n->suffix))
-					strcpy(s, str_toupper_z(localized_abbrev_days[tm->tm_wday]));
+					strcpy(s, str_toupper_z(localized_abbrev_days[tm->tm_wday], collid));
 				else
-					strcpy(s, str_toupper_z(days_short[tm->tm_wday]));
+					strcpy(s, str_toupper_z(days_short[tm->tm_wday], collid));
 				s += strlen(s);
 				break;
 			case DCH_Dy:
 				INVALID_FOR_INTERVAL;
 				if (S_TM(n->suffix))
-					strcpy(s, str_initcap_z(localized_abbrev_days[tm->tm_wday]));
+					strcpy(s, str_initcap_z(localized_abbrev_days[tm->tm_wday], collid));
 				else
 					strcpy(s, days_short[tm->tm_wday]);
 				s += strlen(s);
@@ -2310,7 +2346,7 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
 			case DCH_dy:
 				INVALID_FOR_INTERVAL;
 				if (S_TM(n->suffix))
-					strcpy(s, str_tolower_z(localized_abbrev_days[tm->tm_wday]));
+					strcpy(s, str_tolower_z(localized_abbrev_days[tm->tm_wday], collid));
 				else
 				{
 					strcpy(s, days_short[tm->tm_wday]);
@@ -2846,7 +2882,7 @@ DCH_cache_search(char *str)
  * for formatting.
  */
 static text *
-datetime_to_char_body(TmToChar *tmtc, text *fmt, bool is_interval)
+datetime_to_char_body(TmToChar *tmtc, text *fmt, bool is_interval, Oid collid)
 {
 	FormatNode *format;
 	char	   *fmt_str,
@@ -2912,7 +2948,7 @@ datetime_to_char_body(TmToChar *tmtc, text *fmt, bool is_interval)
 	}
 
 	/* The real work is here */
-	DCH_to_char(format, is_interval, tmtc, result);
+	DCH_to_char(format, is_interval, tmtc, result, collid);
 
 	if (!incache)
 		pfree(format);
@@ -2959,7 +2995,7 @@ timestamp_to_char(PG_FUNCTION_ARGS)
 	tm->tm_wday = (thisdate + 1) % 7;
 	tm->tm_yday = thisdate - date2j(tm->tm_year, 1, 1) + 1;
 
-	if (!(res = datetime_to_char_body(&tmtc, fmt, false)))
+	if (!(res = datetime_to_char_body(&tmtc, fmt, false, PG_GET_COLLATION())))
 		PG_RETURN_NULL();
 
 	PG_RETURN_TEXT_P(res);
@@ -2991,7 +3027,7 @@ timestamptz_to_char(PG_FUNCTION_ARGS)
 	tm->tm_wday = (thisdate + 1) % 7;
 	tm->tm_yday = thisdate - date2j(tm->tm_year, 1, 1) + 1;
 
-	if (!(res = datetime_to_char_body(&tmtc, fmt, false)))
+	if (!(res = datetime_to_char_body(&tmtc, fmt, false, PG_GET_COLLATION())))
 		PG_RETURN_NULL();
 
 	PG_RETURN_TEXT_P(res);
@@ -3023,7 +3059,7 @@ interval_to_char(PG_FUNCTION_ARGS)
 	/* wday is meaningless, yday approximates the total span in days */
 	tm->tm_yday = (tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon) * DAYS_PER_MONTH + tm->tm_mday;
 
-	if (!(res = datetime_to_char_body(&tmtc, fmt, true)))
+	if (!(res = datetime_to_char_body(&tmtc, fmt, true, PG_GET_COLLATION())))
 		PG_RETURN_NULL();
 
 	PG_RETURN_TEXT_P(res);
@@ -4123,7 +4159,7 @@ NUM_numpart_to_char(NUMProc *Np, int id)
  */
 static char *
 NUM_processor(FormatNode *node, NUMDesc *Num, char *inout, char *number,
-			  int plen, int sign, bool is_to_char)
+			  int plen, int sign, bool is_to_char, Oid collid)
 {
 	FormatNode *n;
 	NUMProc		_Np,
@@ -4403,12 +4439,12 @@ NUM_processor(FormatNode *node, NUMDesc *Num, char *inout, char *number,
 				case NUM_rn:
 					if (IS_FILLMODE(Np->Num))
 					{
-						strcpy(Np->inout_p, str_tolower_z(Np->number_p));
+						strcpy(Np->inout_p, str_tolower_z(Np->number_p, collid));
 						Np->inout_p += strlen(Np->inout_p) - 1;
 					}
 					else
 					{
-						sprintf(Np->inout_p, "%15s", str_tolower_z(Np->number_p));
+						sprintf(Np->inout_p, "%15s", str_tolower_z(Np->number_p, collid));
 						Np->inout_p += strlen(Np->inout_p) - 1;
 					}
 					break;
@@ -4541,7 +4577,7 @@ do { \
  */
 #define NUM_TOCHAR_finish \
 do { \
-	NUM_processor(format, &Num, VARDATA(result), numstr, plen, sign, true); \
+	NUM_processor(format, &Num, VARDATA(result), numstr, plen, sign, true, PG_GET_COLLATION()); \
 									\
 	if (shouldFree)					\
 		pfree(format);				\
@@ -4583,7 +4619,7 @@ numeric_to_number(PG_FUNCTION_ARGS)
 	numstr = (char *) palloc((len * NUM_MAX_ITEM_SIZ) + 1);
 
 	NUM_processor(format, &Num, VARDATA(value), numstr,
-				  VARSIZE(value) - VARHDRSZ, 0, false);
+				  VARSIZE(value) - VARHDRSZ, 0, false, PG_GET_COLLATION());
 
 	scale = Num.post;
 	precision = Max(0, Num.pre) + scale;

src/backend/utils/adt/like.c

@@ -39,7 +39,7 @@ static int	UTF8_MatchText(char *t, int tlen, char *p, int plen);
 static int	SB_IMatchText(char *t, int tlen, char *p, int plen);
 
 static int	GenericMatchText(char *s, int slen, char *p, int plen);
-static int	Generic_Text_IC_like(text *str, text *pat);
+static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
  * Support routine for MatchText. Compares given multibyte streams
@@ -133,7 +133,7 @@ GenericMatchText(char *s, int slen, char *p, int plen)
 }
 
 static inline int
-Generic_Text_IC_like(text *str, text *pat)
+Generic_Text_IC_like(text *str, text *pat, Oid collation)
 {
 	char	   *s,
 			   *p;
@@ -149,10 +149,10 @@ Generic_Text_IC_like(text *str, text *pat)
 	if (pg_database_encoding_max_length() > 1)
 	{
 		/* lower's result is never packed, so OK to use old macros here */
-		pat = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(pat)));
+		pat = DatumGetTextP(DirectFunctionCall1WithCollation(lower, collation, PointerGetDatum(pat)));
 		p = VARDATA(pat);
 		plen = (VARSIZE(pat) - VARHDRSZ);
-		str = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(str)));
+		str = DatumGetTextP(DirectFunctionCall1WithCollation(lower, collation, PointerGetDatum(str)));
 		s = VARDATA(str);
 		slen = (VARSIZE(str) - VARHDRSZ);
 		if (GetDatabaseEncoding() == PG_UTF8)
@@ -314,7 +314,7 @@ nameiclike(PG_FUNCTION_ARGS)
 
 	strtext = DatumGetTextP(DirectFunctionCall1(name_text,
 												NameGetDatum(str)));
-	result = (Generic_Text_IC_like(strtext, pat) == LIKE_TRUE);
+	result = (Generic_Text_IC_like(strtext, pat, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -329,7 +329,7 @@ nameicnlike(PG_FUNCTION_ARGS)
 
 	strtext = DatumGetTextP(DirectFunctionCall1(name_text,
 												NameGetDatum(str)));
-	result = (Generic_Text_IC_like(strtext, pat) != LIKE_TRUE);
+	result = (Generic_Text_IC_like(strtext, pat, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -341,7 +341,7 @@ texticlike(PG_FUNCTION_ARGS)
 	text	   *pat = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = (Generic_Text_IC_like(str, pat) == LIKE_TRUE);
+	result = (Generic_Text_IC_like(str, pat, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -353,7 +353,7 @@ texticnlike(PG_FUNCTION_ARGS)
 	text	   *pat = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = (Generic_Text_IC_like(str, pat) != LIKE_TRUE);
+	result = (Generic_Text_IC_like(str, pat, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }

src/backend/utils/adt/oracle_compat.c

@@ -47,7 +47,8 @@ lower(PG_FUNCTION_ARGS)
 	text	   *result;
 
 	out_string = str_tolower(VARDATA_ANY(in_string),
-							 VARSIZE_ANY_EXHDR(in_string));
+							 VARSIZE_ANY_EXHDR(in_string),
+							 PG_GET_COLLATION());
 	result = cstring_to_text(out_string);
 	pfree(out_string);
 
@@ -77,7 +78,8 @@ upper(PG_FUNCTION_ARGS)
 	text	   *result;
 
 	out_string = str_toupper(VARDATA_ANY(in_string),
-							 VARSIZE_ANY_EXHDR(in_string));
+							 VARSIZE_ANY_EXHDR(in_string),
+							 PG_GET_COLLATION());
 	result = cstring_to_text(out_string);
 	pfree(out_string);
 
@@ -110,7 +112,8 @@ initcap(PG_FUNCTION_ARGS)
 	text	   *result;
 
 	out_string = str_initcap(VARDATA_ANY(in_string),
-							 VARSIZE_ANY_EXHDR(in_string));
+							 VARSIZE_ANY_EXHDR(in_string),
+							 PG_GET_COLLATION());
 	result = cstring_to_text(out_string);
 	pfree(out_string);
 

src/backend/utils/adt/pg_locale.c

@@ -54,10 +54,13 @@
 #include <locale.h>
 #include <time.h>
 
+#include "catalog/pg_collation.h"
 #include "catalog/pg_control.h"
 #include "mb/pg_wchar.h"
+#include "utils/hsearch.h"
 #include "utils/memutils.h"
 #include "utils/pg_locale.h"
+#include "utils/syscache.h"
 
 #ifdef WIN32
 #include <shlwapi.h>
@@ -100,6 +103,11 @@ static char lc_time_envbuf[LC_ENV_BUFSIZE];
 static char *IsoLocaleName(const char *);		/* MSVC specific */
 #endif
 
+static HTAB *locale_cness_cache = NULL;
+#ifdef HAVE_LOCALE_T
+static HTAB *locale_t_cache = NULL;
+#endif
+
 
 /*
  * pg_perm_setlocale
@@ -305,16 +313,90 @@ locale_messages_assign(const char *value, bool doit, GucSource source)
 
 
 /*
- * We'd like to cache whether LC_COLLATE is C (or POSIX), so we can
- * optimize a few code paths in various places.
+ * We'd like to cache whether LC_COLLATE or LC_CTYPE is C (or POSIX),
+ * so we can optimize a few code paths in various places.
+ *
+ * Note that some code relies on this not reporting false negatives
+ * (that is, saying it's not C when it is).  For example, char2wchar()
+ * could fail if the locale is C, so str_tolower() shouldn't call it
+ * in that case.
  */
+
+struct locale_cness_cache_entry
+{
+	Oid			collid;
+	bool		collate_is_c;
+	bool		ctype_is_c;
+};
+
+static void
+init_locale_cness_cache(void)
+{
+	HASHCTL		ctl;
+
+	memset(&ctl, 0, sizeof(ctl));
+	ctl.keysize = sizeof(Oid);
+	ctl.entrysize = sizeof(struct locale_cness_cache_entry);
+	ctl.hash = oid_hash;
+	locale_cness_cache = hash_create("locale C-ness cache", 1000, &ctl, HASH_ELEM | HASH_FUNCTION);
+}
+
+/*
+ * Handle caching of locale "C-ness" for nondefault collation objects.
+ * Relying on the system cache directly isn't fast enough.
+ */
+static bool
+lookup_collation_cness(Oid collation, int category)
+{
+	struct locale_cness_cache_entry *cache_entry;
+	bool		found;
+	HeapTuple	tp;
+	char	   *localeptr;
+
+	Assert(OidIsValid(collation));
+	Assert(category == LC_COLLATE || category == LC_CTYPE);
+
+	if (!locale_cness_cache)
+		init_locale_cness_cache();
+
+	cache_entry = hash_search(locale_cness_cache, &collation, HASH_ENTER, &found);
+	if (found)
+	{
+		if (category == LC_COLLATE)
+			return cache_entry->collate_is_c;
+		else
+			return cache_entry->ctype_is_c;
+	}
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collation));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", collation);
+
+	localeptr = NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate);
+	cache_entry->collate_is_c = (strcmp(localeptr, "C") == 0) || (strcmp(localeptr, "POSIX") == 0);
+
+	localeptr = NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype);
+	cache_entry->ctype_is_c = (strcmp(localeptr, "C") == 0) || (strcmp(localeptr, "POSIX") == 0);
+
+	ReleaseSysCache(tp);
+
+	return category == LC_COLLATE ? cache_entry->collate_is_c : cache_entry->ctype_is_c;
+}
+
+
 bool
-lc_collate_is_c(void)
+lc_collate_is_c(Oid collation)
 {
 	/* Cache result so we only have to compute it once */
 	static int	result = -1;
 	char	   *localeptr;
 
+	if (!OidIsValid(collation))
+		return false;
+
+	if (collation != DEFAULT_COLLATION_OID)
+		return lookup_collation_cness(collation, LC_COLLATE);
+
 	if (result >= 0)
 		return (bool) result;
 	localeptr = setlocale(LC_COLLATE, NULL);
@@ -331,17 +413,19 @@ lc_collate_is_c(void)
 }
 
 
-/*
- * We'd like to cache whether LC_CTYPE is C (or POSIX), so we can
- * optimize a few code paths in various places.
- */
 bool
-lc_ctype_is_c(void)
+lc_ctype_is_c(Oid collation)
 {
 	/* Cache result so we only have to compute it once */
 	static int	result = -1;
 	char	   *localeptr;
 
+	if (!OidIsValid(collation))
+		return false;
+
+	if (collation != DEFAULT_COLLATION_OID)
+		return lookup_collation_cness(collation, LC_CTYPE);
+
 	if (result >= 0)
 		return (bool) result;
 	localeptr = setlocale(LC_CTYPE, NULL);
@@ -483,7 +567,7 @@ PGLC_localeconv(void)
 	/* Get formatting information for numeric */
 	setlocale(LC_NUMERIC, locale_numeric);
 	extlconv = localeconv();
-	encoding = pg_get_encoding_from_locale(locale_numeric);
+	encoding = pg_get_encoding_from_locale(locale_numeric, true);
 
 	decimal_point = db_encoding_strdup(encoding, extlconv->decimal_point);
 	thousands_sep = db_encoding_strdup(encoding, extlconv->thousands_sep);
@@ -497,7 +581,7 @@ PGLC_localeconv(void)
 	/* Get formatting information for monetary */
 	setlocale(LC_MONETARY, locale_monetary);
 	extlconv = localeconv();
-	encoding = pg_get_encoding_from_locale(locale_monetary);
+	encoding = pg_get_encoding_from_locale(locale_monetary, true);
 
 	/*
 	 * Must copy all values since restoring internal settings may overwrite
@@ -758,3 +842,118 @@ IsoLocaleName(const char *winlocname)
 }
 
 #endif   /* WIN32 && LC_MESSAGES */
+
+
+#ifdef HAVE_LOCALE_T
+struct locale_t_cache_entry
+{
+	Oid			collid;
+	locale_t	locale;
+};
+
+static void
+init_locale_t_cache(void)
+{
+	HASHCTL		ctl;
+
+	memset(&ctl, 0, sizeof(ctl));
+	ctl.keysize = sizeof(Oid);
+	ctl.entrysize = sizeof(struct locale_t_cache_entry);
+	ctl.hash = oid_hash;
+	locale_t_cache = hash_create("locale_t cache", 1000, &ctl, HASH_ELEM | HASH_FUNCTION);
+}
+#endif /* HAVE_LOCALE_T */
+
+/*
+ * Create a locale_t from a collation OID.  Results are cached for the
+ * lifetime of the backend.  Thus, do not free the result with
+ * freelocale().
+ *
+ * As a special optimization, the default/database collation returns
+ * 0.  Callers should then revert to the non-locale_t-enabled code
+ * path.  In fact, they shouldn't call this function at all when they
+ * are dealing with the default locale.  That can save quite a bit in
+ * hotspots.
+ *
+ * For simplicity, we always generate COLLATE + CTYPE even though we
+ * might only need one of them.  Since this is called only once per
+ * session, it shouldn't cost much.
+ */
+pg_locale_t
+pg_newlocale_from_collation(Oid collid)
+{
+#ifdef HAVE_LOCALE_T
+	HeapTuple	tp;
+	const char *collcollate;
+	const char *collctype;
+	locale_t	result;
+	struct locale_t_cache_entry *cache_entry;
+	bool		found;
+
+	if (collid == DEFAULT_COLLATION_OID)
+		return (locale_t) 0;
+
+	if (!OidIsValid(collid))
+		elog(ERROR, "locale operation to be invoked, but no collation was derived");
+
+	if (!locale_t_cache)
+		init_locale_t_cache();
+
+	cache_entry = hash_search(locale_t_cache, &collid, HASH_ENTER, &found);
+	if (found)
+		return cache_entry->locale;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", collid);
+
+	collcollate = NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate);
+	collctype = NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype);
+
+	if (strcmp(collcollate, collctype) == 0)
+	{
+		result = newlocale(LC_COLLATE_MASK | LC_CTYPE_MASK, collcollate, NULL);
+		if (!result)
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not create locale \"%s\": %m", collcollate)));
+	}
+	else
+	{
+		locale_t loc1;
+
+		loc1 = newlocale(LC_COLLATE_MASK, collcollate, NULL);
+		if (!loc1)
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not create locale \"%s\": %m", collcollate)));
+		result = newlocale(LC_CTYPE_MASK, collctype, loc1);
+		if (!result)
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not create locale \"%s\": %m", collctype)));
+	}
+
+	ReleaseSysCache(tp);
+
+	cache_entry->locale = result;
+
+	return result;
+#else /* not HAVE_LOCALE_T */
+	/*
+	 * For platforms that don't support locale_t, check that we are
+	 * dealing with the default locale.  It's unlikely that we'll get
+	 * here, but it's possible if users are creating collations even
+	 * though they are not supported, or they are mixing builds in odd
+	 * ways.
+	 */
+	if (!OidIsValid(collid))
+		elog(ERROR, "locale operation to be invoked, but no collation was derived");
+	else if (collid != DEFAULT_COLLATION_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondefault collations are not supported on this platform")));
+
+	return 0;
+#endif /* not HAVE_LOCALE_T */
+}

src/backend/utils/adt/ruleutils.c

@@ -23,6 +23,7 @@
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_authid.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_language.h"
@@ -233,7 +234,7 @@ static void get_from_clause_item(Node *jtnode, Query *query,
 					 deparse_context *context);
 static void get_from_clause_alias(Alias *alias, RangeTblEntry *rte,
 					  deparse_context *context);
-static void get_from_clause_coldeflist(List *names, List *types, List *typmods,
+static void get_from_clause_coldeflist(List *names, List *types, List *typmods, List *collations,
 						   deparse_context *context);
 static void get_opclass_name(Oid opclass, Oid actual_datatype,
 				 StringInfo buf);
@@ -788,9 +789,11 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 	Oid			indrelid;
 	int			keyno;
 	Oid			keycoltype;
+	Datum		indcollDatum;
 	Datum		indclassDatum;
 	Datum		indoptionDatum;
 	bool		isnull;
+	oidvector  *indcollation;
 	oidvector  *indclass;
 	int2vector *indoption;
 	StringInfoData buf;
@@ -808,11 +811,17 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 	indrelid = idxrec->indrelid;
 	Assert(indexrelid == idxrec->indexrelid);
 
-	/* Must get indclass and indoption the hard way */
+	/* Must get indcollation, indclass, and indoption the hard way */
+	indcollDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
+								   Anum_pg_index_indcollation, &isnull);
+	Assert(!isnull);
+	indcollation = (oidvector *) DatumGetPointer(indcollDatum);
+
 	indclassDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
 									Anum_pg_index_indclass, &isnull);
 	Assert(!isnull);
 	indclass = (oidvector *) DatumGetPointer(indclassDatum);
+
 	indoptionDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
 									 Anum_pg_index_indoption, &isnull);
 	Assert(!isnull);
@@ -928,6 +937,13 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 
 		if (!attrsOnly && (!colno || colno == keyno + 1))
 		{
+			Oid coll;
+
+			/* Add collation, if not default */
+			coll = indcollation->values[keyno];
+			if (coll && coll != DEFAULT_COLLATION_OID && coll != get_attcollation(indrelid, attnum))
+				appendStringInfo(&buf, " COLLATE %s", generate_collation_name((indcollation->values[keyno])));
+
 			/* Add the operator class name, if not default */
 			get_opclass_name(indclass->values[keyno], keycoltype, &buf);
 
@@ -5054,6 +5070,20 @@ get_rule_expr(Node *node, deparse_context *context,
 			}
 			break;
 
+		case T_CollateClause:
+			{
+				CollateClause *collate = (CollateClause *) node;
+				Node	   *arg = (Node *) collate->arg;
+
+				if (!PRETTY_PAREN(context))
+					appendStringInfoChar(buf, '(');
+				get_rule_expr_paren(arg, context, false, node);
+				appendStringInfo(buf, " COLLATE %s", generate_collation_name(collate->collOid));
+				if (!PRETTY_PAREN(context))
+					appendStringInfoChar(buf, ')');
+			}
+			break;
+
 		case T_CoerceViaIO:
 			{
 				CoerceViaIO *iocoerce = (CoerceViaIO *) node;
@@ -6345,6 +6375,7 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 				get_from_clause_coldeflist(rte->eref->colnames,
 										   rte->funccoltypes,
 										   rte->funccoltypmods,
+										   rte->funccolcollations,
 										   context);
 			}
 			else
@@ -6543,35 +6574,42 @@ get_from_clause_alias(Alias *alias, RangeTblEntry *rte,
  * responsible for ensuring that an alias or AS is present before it.
  */
 static void
-get_from_clause_coldeflist(List *names, List *types, List *typmods,
+get_from_clause_coldeflist(List *names, List *types, List *typmods, List *collations,
 						   deparse_context *context)
 {
 	StringInfo	buf = context->buf;
 	ListCell   *l1;
 	ListCell   *l2;
 	ListCell   *l3;
+	ListCell   *l4;
 	int			i = 0;
 
 	appendStringInfoChar(buf, '(');
 
 	l2 = list_head(types);
 	l3 = list_head(typmods);
+	l4 = list_head(collations);
 	foreach(l1, names)
 	{
 		char	   *attname = strVal(lfirst(l1));
 		Oid			atttypid;
 		int32		atttypmod;
+		Oid			attcollation;
 
 		atttypid = lfirst_oid(l2);
 		l2 = lnext(l2);
 		atttypmod = lfirst_int(l3);
 		l3 = lnext(l3);
+		attcollation = lfirst_oid(l4);
+		l4 = lnext(l4);
 
 		if (i > 0)
 			appendStringInfo(buf, ", ");
 		appendStringInfo(buf, "%s %s",
 						 quote_identifier(attname),
 						 format_type_with_typemod(atttypid, atttypmod));
+		if (attcollation && attcollation != DEFAULT_COLLATION_OID)
+			appendStringInfo(buf, " COLLATE %s", generate_collation_name(attcollation));
 		i++;
 	}
 
@@ -7038,6 +7076,39 @@ generate_operator_name(Oid operid, Oid arg1, Oid arg2)
 	return buf.data;
 }
 
+/*
+ * generate_collation_name
+ *		Compute the name to display for a collation specified by OID
+ *
+ * The result includes all necessary quoting and schema-prefixing.
+ */
+char *
+generate_collation_name(Oid collid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	char	   *collname;
+	char	   *nspname;
+	char	   *result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", collid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	collname = NameStr(colltup->collname);
+
+	if (!CollationIsVisible(collid))
+		nspname = get_namespace_name(colltup->collnamespace);
+	else
+		nspname = NULL;
+
+	result = quote_qualified_identifier(nspname, collname);
+
+	ReleaseSysCache(tp);
+
+	return result;
+}
+
 /*
  * Given a C string, produce a TEXT datum.
  *

src/backend/utils/adt/selfuncs.c

@@ -94,6 +94,7 @@
 #include "access/gin.h"
 #include "access/sysattr.h"
 #include "catalog/index.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_opfamily.h"
 #include "catalog/pg_statistic.h"
 #include "catalog/pg_type.h"
@@ -144,7 +145,7 @@ static double eqjoinsel_inner(Oid operator,
 static double eqjoinsel_semi(Oid operator,
 			   VariableStatData *vardata1, VariableStatData *vardata2);
 static bool convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
-				  Datum lobound, Datum hibound, Oid boundstypid,
+				  Datum lobound, Datum hibound, Oid boundstypid, Oid boundscollid,
 				  double *scaledlobound, double *scaledhibound);
 static double convert_numeric_to_scalar(Datum value, Oid typid);
 static void convert_string_to_scalar(char *value,
@@ -163,10 +164,10 @@ static double convert_one_string_to_scalar(char *value,
 							 int rangelo, int rangehi);
 static double convert_one_bytea_to_scalar(unsigned char *value, int valuelen,
 							int rangelo, int rangehi);
-static char *convert_string_datum(Datum value, Oid typid);
+static char *convert_string_datum(Datum value, Oid typid, Oid collid);
 static double convert_timevalue_to_scalar(Datum value, Oid typid);
 static bool get_variable_range(PlannerInfo *root, VariableStatData *vardata,
-				   Oid sortop, Datum *min, Datum *max);
+				   Oid sortop, Oid collation, Datum *min, Datum *max);
 static bool get_actual_variable_range(PlannerInfo *root,
 						  VariableStatData *vardata,
 						  Oid sortop,
@@ -513,6 +514,7 @@ scalarineqsel(PlannerInfo *root, Oid operator, bool isgt,
 	stats = (Form_pg_statistic) GETSTRUCT(vardata->statsTuple);
 
 	fmgr_info(get_opcode(operator), &opproc);
+	fmgr_info_collation(vardata->attcollation, &opproc);
 
 	/*
 	 * If we have most-common-values info, add up the fractions of the MCV
@@ -837,7 +839,7 @@ ineq_histogram_selectivity(PlannerInfo *root,
 				 */
 				if (convert_to_scalar(constval, consttype, &val,
 									  values[i - 1], values[i],
-									  vardata->vartype,
+									  vardata->vartype, vardata->attcollation,
 									  &low, &high))
 				{
 					if (high <= low)
@@ -1249,6 +1251,7 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype, bool negate)
 
 		/* Try to use the histogram entries to get selectivity */
 		fmgr_info(get_opcode(operator), &opproc);
+		fmgr_info_collation(DEFAULT_COLLATION_OID, &opproc);
 
 		selec = histogram_selectivity(&vardata, &opproc, constval, true,
 									  10, 1, &hist_size);
@@ -2585,7 +2588,7 @@ icnlikejoinsel(PG_FUNCTION_ARGS)
  */
 void
 mergejoinscansel(PlannerInfo *root, Node *clause,
-				 Oid opfamily, int strategy, bool nulls_first,
+				 Oid opfamily, Oid collation, int strategy, bool nulls_first,
 				 Selectivity *leftstart, Selectivity *leftend,
 				 Selectivity *rightstart, Selectivity *rightend)
 {
@@ -2754,20 +2757,20 @@ mergejoinscansel(PlannerInfo *root, Node *clause,
 	/* Try to get ranges of both inputs */
 	if (!isgt)
 	{
-		if (!get_variable_range(root, &leftvar, lstatop,
+		if (!get_variable_range(root, &leftvar, lstatop, collation,
 								&leftmin, &leftmax))
 			goto fail;			/* no range available from stats */
-		if (!get_variable_range(root, &rightvar, rstatop,
+		if (!get_variable_range(root, &rightvar, rstatop, collation,
 								&rightmin, &rightmax))
 			goto fail;			/* no range available from stats */
 	}
 	else
 	{
 		/* need to swap the max and min */
-		if (!get_variable_range(root, &leftvar, lstatop,
+		if (!get_variable_range(root, &leftvar, lstatop, collation,
 								&leftmax, &leftmin))
 			goto fail;			/* no range available from stats */
-		if (!get_variable_range(root, &rightvar, rstatop,
+		if (!get_variable_range(root, &rightvar, rstatop, collation,
 								&rightmax, &rightmin))
 			goto fail;			/* no range available from stats */
 	}
@@ -3368,7 +3371,7 @@ estimate_hash_bucketsize(PlannerInfo *root, Node *hashkey, double nbuckets)
  */
 static bool
 convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
-				  Datum lobound, Datum hibound, Oid boundstypid,
+				  Datum lobound, Datum hibound, Oid boundstypid, Oid boundscollid,
 				  double *scaledlobound, double *scaledhibound)
 {
 	/*
@@ -3421,9 +3424,9 @@ convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue,
 		case TEXTOID:
 		case NAMEOID:
 			{
-				char	   *valstr = convert_string_datum(value, valuetypid);
-				char	   *lostr = convert_string_datum(lobound, boundstypid);
-				char	   *histr = convert_string_datum(hibound, boundstypid);
+				char	   *valstr = convert_string_datum(value, valuetypid, boundscollid);
+				char	   *lostr = convert_string_datum(lobound, boundstypid, boundscollid);
+				char	   *histr = convert_string_datum(hibound, boundstypid, boundscollid);
 
 				convert_string_to_scalar(valstr, scaledvalue,
 										 lostr, scaledlobound,
@@ -3667,7 +3670,7 @@ convert_one_string_to_scalar(char *value, int rangelo, int rangehi)
  * before continuing, so as to generate correct locale-specific results.
  */
 static char *
-convert_string_datum(Datum value, Oid typid)
+convert_string_datum(Datum value, Oid typid, Oid collid)
 {
 	char	   *val;
 
@@ -3700,7 +3703,7 @@ convert_string_datum(Datum value, Oid typid)
 			return NULL;
 	}
 
-	if (!lc_collate_is_c())
+	if (!lc_collate_is_c(collid))
 	{
 		char	   *xfrmstr;
 		size_t		xfrmlen;
@@ -4099,6 +4102,7 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
 		vardata->rel = find_base_rel(root, var->varno);
 		vardata->atttype = var->vartype;
 		vardata->atttypmod = var->vartypmod;
+		vardata->attcollation = var->varcollid;
 		vardata->isunique = has_unique_index(vardata->rel, var->varattno);
 
 		rte = root->simple_rte_array[var->varno];
@@ -4184,6 +4188,7 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
 	vardata->var = node;
 	vardata->atttype = exprType(node);
 	vardata->atttypmod = exprTypmod(node);
+	vardata->attcollation = exprCollation(node);
 
 	if (onerel)
 	{
@@ -4392,7 +4397,7 @@ get_variable_numdistinct(VariableStatData *vardata)
  * be "<" not ">", as only the former is likely to be found in pg_statistic.
  */
 static bool
-get_variable_range(PlannerInfo *root, VariableStatData *vardata, Oid sortop,
+get_variable_range(PlannerInfo *root, VariableStatData *vardata, Oid sortop, Oid collation,
 				   Datum *min, Datum *max)
 {
 	Datum		tmin = 0;
@@ -4477,6 +4482,7 @@ get_variable_range(PlannerInfo *root, VariableStatData *vardata, Oid sortop,
 		FmgrInfo	opproc;
 
 		fmgr_info(get_opcode(sortop), &opproc);
+		fmgr_info_collation(collation, &opproc);
 
 		for (i = 0; i < nvalues; i++)
 		{
@@ -5482,7 +5488,7 @@ make_greater_string(const Const *str_const, FmgrInfo *ltproc)
 	{
 		workstr = TextDatumGetCString(str_const->constvalue);
 		len = strlen(workstr);
-		if (lc_collate_is_c() || len == 0)
+		if (lc_collate_is_c(ltproc->fn_collation) || len == 0)
 			cmpstr = str_const->constvalue;
 		else
 		{
@@ -5494,11 +5500,11 @@ make_greater_string(const Const *str_const, FmgrInfo *ltproc)
 				char	   *best;
 
 				best = "Z";
-				if (varstr_cmp(best, 1, "z", 1) < 0)
+				if (varstr_cmp(best, 1, "z", 1, DEFAULT_COLLATION_OID) < 0)
 					best = "z";
-				if (varstr_cmp(best, 1, "y", 1) < 0)
+				if (varstr_cmp(best, 1, "y", 1, DEFAULT_COLLATION_OID) < 0)
 					best = "y";
-				if (varstr_cmp(best, 1, "9", 1) < 0)
+				if (varstr_cmp(best, 1, "9", 1, DEFAULT_COLLATION_OID) < 0)
 					best = "9";
 				suffixchar = *best;
 			}

src/backend/utils/adt/varchar.c

@@ -737,7 +737,8 @@ bpcharlt(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -757,7 +758,8 @@ bpcharle(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -777,7 +779,8 @@ bpchargt(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -797,7 +800,8 @@ bpcharge(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -817,7 +821,8 @@ bpcharcmp(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -837,7 +842,8 @@ bpchar_larger(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_RETURN_BPCHAR_P((cmp >= 0) ? arg1 : arg2);
 }
@@ -854,7 +860,8 @@ bpchar_smaller(PG_FUNCTION_ARGS)
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2);
+	cmp = varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+					 PG_GET_COLLATION());
 
 	PG_RETURN_BPCHAR_P((cmp <= 0) ? arg1 : arg2);
 }

src/backend/utils/adt/varlena.c

@@ -18,6 +18,7 @@
 #include <limits.h>
 
 #include "access/tuptoaster.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/md5.h"
 #include "libpq/pqformat.h"
@@ -55,7 +56,7 @@ typedef struct
 #define PG_GETARG_UNKNOWN_P_COPY(n) DatumGetUnknownPCopy(PG_GETARG_DATUM(n))
 #define PG_RETURN_UNKNOWN_P(x)		PG_RETURN_POINTER(x)
 
-static int	text_cmp(text *arg1, text *arg2);
+static int	text_cmp(text *arg1, text *arg2, Oid collid);
 static int32 text_length(Datum str);
 static int	text_position(text *t1, text *t2);
 static void text_position_setup(text *t1, text *t2, TextPositionState *state);
@@ -1274,7 +1275,7 @@ text_position_cleanup(TextPositionState *state)
  * whether arg1 is less than, equal to, or greater than arg2.
  */
 int
-varstr_cmp(char *arg1, int len1, char *arg2, int len2)
+varstr_cmp(char *arg1, int len1, char *arg2, int len2, Oid collid)
 {
 	int			result;
 
@@ -1284,7 +1285,7 @@ varstr_cmp(char *arg1, int len1, char *arg2, int len2)
 	 * slower, so we optimize the case where LC_COLLATE is C.  We also try to
 	 * optimize relatively-short strings by avoiding palloc/pfree overhead.
 	 */
-	if (lc_collate_is_c())
+	if (lc_collate_is_c(collid))
 	{
 		result = memcmp(arg1, arg2, Min(len1, len2));
 		if ((result == 0) && (len1 != len2))
@@ -1298,6 +1299,10 @@ varstr_cmp(char *arg1, int len1, char *arg2, int len2)
 		char		a2buf[STACKBUFLEN];
 		char	   *a1p,
 				   *a2p;
+		pg_locale_t	mylocale = 0;
+
+		if (collid != DEFAULT_COLLATION_OID)
+			mylocale = pg_newlocale_from_collation(collid);
 
 #ifdef WIN32
 		/* Win32 does not have UTF-8, so we need to map to UTF-16 */
@@ -1398,6 +1403,11 @@ varstr_cmp(char *arg1, int len1, char *arg2, int len2)
 		memcpy(a2p, arg2, len2);
 		a2p[len2] = '\0';
 
+#ifdef HAVE_LOCALE_T
+		if (mylocale)
+			result = strcoll_l(a1p, a2p, mylocale);
+		else
+#endif
 		result = strcoll(a1p, a2p);
 
 		/*
@@ -1424,7 +1434,7 @@ varstr_cmp(char *arg1, int len1, char *arg2, int len2)
  * Returns -1, 0 or 1
  */
 static int
-text_cmp(text *arg1, text *arg2)
+text_cmp(text *arg1, text *arg2, Oid collid)
 {
 	char	   *a1p,
 			   *a2p;
@@ -1437,7 +1447,7 @@ text_cmp(text *arg1, text *arg2)
 	len1 = VARSIZE_ANY_EXHDR(arg1);
 	len2 = VARSIZE_ANY_EXHDR(arg2);
 
-	return varstr_cmp(a1p, len1, a2p, len2);
+	return varstr_cmp(a1p, len1, a2p, len2, collid);
 }
 
 /*
@@ -1519,7 +1529,7 @@ text_lt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = (text_cmp(arg1, arg2) < 0);
+	result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) < 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1534,7 +1544,7 @@ text_le(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = (text_cmp(arg1, arg2) <= 0);
+	result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) <= 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1549,7 +1559,7 @@ text_gt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = (text_cmp(arg1, arg2) > 0);
+	result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) > 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1564,7 +1574,7 @@ text_ge(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	bool		result;
 
-	result = (text_cmp(arg1, arg2) >= 0);
+	result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) >= 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1579,7 +1589,7 @@ bttextcmp(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int32		result;
 
-	result = text_cmp(arg1, arg2);
+	result = text_cmp(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1595,7 +1605,7 @@ text_larger(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	text	   *result;
 
-	result = ((text_cmp(arg1, arg2) > 0) ? arg1 : arg2);
+	result = ((text_cmp(arg1, arg2, PG_GET_COLLATION()) > 0) ? arg1 : arg2);
 
 	PG_RETURN_TEXT_P(result);
 }
@@ -1607,7 +1617,7 @@ text_smaller(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	text	   *result;
 
-	result = ((text_cmp(arg1, arg2) < 0) ? arg1 : arg2);
+	result = ((text_cmp(arg1, arg2, PG_GET_COLLATION()) < 0) ? arg1 : arg2);
 
 	PG_RETURN_TEXT_P(result);
 }

src/backend/utils/cache/lsyscache.c

@@ -20,6 +20,7 @@
 #include "bootstrap/bootstrap.h"
 #include "catalog/pg_amop.h"
 #include "catalog/pg_amproc.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_opclass.h"
@@ -902,6 +903,33 @@ get_atttypmod(Oid relid, AttrNumber attnum)
 		return -1;
 }
 
+/*
+ * get_attcollation
+ *
+ *		Given the relation id and the attribute number,
+ *		return the "attcollation" field from the attribute relation.
+ */
+Oid
+get_attcollation(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+		Oid		result;
+
+		result = att_tup->attcollation;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return InvalidOid;
+}
+
 /*
  * get_atttypetypmod
  *
@@ -931,6 +959,36 @@ get_atttypetypmod(Oid relid, AttrNumber attnum,
 	ReleaseSysCache(tp);
 }
 
+/*				---------- COLLATION CACHE ----------					 */
+
+/*
+ * get_collation_name
+ *		Returns the name of a given pg_collation entry.
+ *
+ * Returns a palloc'd copy of the string, or NULL if no such constraint.
+ *
+ * NOTE: since collation name is not unique, be wary of code that uses this
+ * for anything except preparing error messages.
+ */
+char *
+get_collation_name(Oid colloid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_collation colltup = (Form_pg_collation) GETSTRUCT(tp);
+		char	   *result;
+
+		result = pstrdup(NameStr(colltup->collname));
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return NULL;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
@@ -2523,6 +2581,42 @@ get_typmodout(Oid typid)
 }
 #endif   /* NOT_USED */
 
+/*
+ * get_typcollation
+ *
+ *		Given the type OID, return the type's typcollation attribute.
+ */
+Oid
+get_typcollation(Oid typid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
+		Oid			result;
+
+		result = typtup->typcollation;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return InvalidOid;
+}
+
+
+/*
+ * type_is_collatable
+ *
+ *		Return whether the type cares about collations
+ */
+bool
+type_is_collatable(Oid typid)
+{
+	return OidIsValid(get_typcollation(typid));
+}
+
 
 /*				---------- STATISTICS CACHE ----------					 */