From abb1733922f3ff17a514499883a549f8bd03af44 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Tue, 5 Jan 2016 19:02:13 -0300
Subject: [PATCH] Add scale(numeric)

Author: Marko Tiikkaja
---
 doc/src/sgml/func.sgml                | 13 ++++++
 src/backend/utils/adt/numeric.c       | 17 ++++++++
 src/include/catalog/catversion.h      |  2 +-
 src/include/catalog/pg_proc.h         |  2 +
 src/include/utils/builtins.h          |  1 +
 src/test/regress/expected/numeric.out | 57 +++++++++++++++++++++++++++
 src/test/regress/sql/numeric.sql      | 14 +++++++
 7 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index a0b42c2ddb..8591aa3e5a 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -849,6 +849,19 @@
        <entry><literal>42.44</literal></entry>
       </row>
 
+      <row>
+       <entry>
+        <indexterm>
+         <primary>scale</primary>
+        </indexterm>
+        <literal><function>scale(<type>numeric</type>)</function></literal>
+       </entry>
+       <entry><type>numeric</type></entry>
+       <entry>scale of the argument (the number of decimal digits in the fractional part)</entry>
+       <entry><literal>scale(8.41)</literal></entry>
+       <entry><literal>2</literal></entry>
+      </row>
+
       <row>
        <entry>
         <indexterm>
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index ea79b48a8f..07b264572d 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -2825,6 +2825,23 @@ numeric_power(PG_FUNCTION_ARGS)
 	PG_RETURN_NUMERIC(res);
 }
 
+/*
+ * numeric_scale() -
+ *
+ *	Returns the scale, i.e. the count of decimal digits in the fractional part
+ */
+Datum
+numeric_scale(PG_FUNCTION_ARGS)
+{
+	Numeric		num = PG_GETARG_NUMERIC(0);
+
+	if (NUMERIC_IS_NAN(num))
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT32(NUMERIC_DSCALE(num));
+}
+
+
 
 /* ----------------------------------------------------------------------
  *
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 2c6aa45063..31a132ea98 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201601051
+#define CATALOG_VERSION_NO	201601052
 
 #endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 22d9386ada..9250545d3b 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2361,6 +2361,8 @@ DESCR("exponentiation");
 DATA(insert OID = 2169 ( power					PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 1700 "1700 1700" _null_ _null_ _null_ _null_ _null_	numeric_power _null_ _null_ _null_ ));
 DESCR("exponentiation");
 DATA(insert OID = 1739 ( numeric_power			PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 1700 "1700 1700" _null_ _null_ _null_ _null_ _null_	numeric_power _null_ _null_ _null_ ));
+DATA(insert OID = 8888 ( scale					PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 23 "1700" _null_ _null_ _null_ _null_ _null_ numeric_scale _null_ _null_ _null_ ));
+DESCR("number of decimal digits in the fractional part");
 DATA(insert OID = 1740 ( numeric				PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 1700 "23" _null_ _null_ _null_ _null_ _null_ int4_numeric _null_ _null_ _null_ ));
 DESCR("convert int4 to numeric");
 DATA(insert OID = 1741 ( log					PGNSP PGUID 14 1 0 0 0 f f f f t f i s 1 0 1700 "1700" _null_ _null_ _null_ _null_ _null_ "select pg_catalog.log(10, $1)" _null_ _null_ _null_ ));
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index bbaa2cea7e..b35d20626b 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -1022,6 +1022,7 @@ extern Datum numeric_exp(PG_FUNCTION_ARGS);
 extern Datum numeric_ln(PG_FUNCTION_ARGS);
 extern Datum numeric_log(PG_FUNCTION_ARGS);
 extern Datum numeric_power(PG_FUNCTION_ARGS);
+extern Datum numeric_scale(PG_FUNCTION_ARGS);
 extern Datum int4_numeric(PG_FUNCTION_ARGS);
 extern Datum numeric_int4(PG_FUNCTION_ARGS);
 extern Datum int8_numeric(PG_FUNCTION_ARGS);
diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index caac424744..f1f50560ee 100644
--- a/src/test/regress/expected/numeric.out
+++ b/src/test/regress/expected/numeric.out
@@ -1852,3 +1852,60 @@ select log(3.1954752e47, 9.4792021e-73);
  -1.51613372350688302142917386143459361608600157692779164475351842333265418126982165
 (1 row)
 
+--
+-- Tests for scale()
+--
+select scale(numeric 'NaN');
+ scale 
+-------
+      
+(1 row)
+
+select scale(NULL::numeric);
+ scale 
+-------
+      
+(1 row)
+
+select scale(1.12);
+ scale 
+-------
+     2
+(1 row)
+
+select scale(0);
+ scale 
+-------
+     0
+(1 row)
+
+select scale(0.00);
+ scale 
+-------
+     2
+(1 row)
+
+select scale(1.12345);
+ scale 
+-------
+     5
+(1 row)
+
+select scale(110123.12475871856128);
+ scale 
+-------
+    14
+(1 row)
+
+select scale(-1123.12471856128);
+ scale 
+-------
+    11
+(1 row)
+
+select scale(-13.000000000000000);
+ scale 
+-------
+    15
+(1 row)
+
diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index 0a4d1cb1d2..fc472187d8 100644
--- a/src/test/regress/sql/numeric.sql
+++ b/src/test/regress/sql/numeric.sql
@@ -983,3 +983,17 @@ select log(1.23e-89, 6.4689e45);
 select log(0.99923, 4.58934e34);
 select log(1.000016, 8.452010e18);
 select log(3.1954752e47, 9.4792021e-73);
+
+--
+-- Tests for scale()
+--
+
+select scale(numeric 'NaN');
+select scale(NULL::numeric);
+select scale(1.12);
+select scale(0);
+select scale(0.00);
+select scale(1.12345);
+select scale(110123.12475871856128);
+select scale(-1123.12471856128);
+select scale(-13.000000000000000);