diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 5f89db5857..028ef10d91 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -1393,6 +1393,30 @@ The commands accepted in walsender mode are:
+
+ SHOW name
+ SHOW
+
+
+
+ Requests the server to send the current setting of a run-time parameter.
+ This is similar to the SQL command .
+
+
+
+
+ name
+
+
+ The name of a run-time parameter. Available parameters are documented
+ in .
+
+
+
+
+
+
+
TIMELINE_HISTORY tli
TIMELINE_HISTORY
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 54a32c0223..083c0303dc 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -20,6 +20,7 @@
#include "postgres.h"
#include "access/htup_details.h"
+#include "catalog/pg_collation.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "parser/parse_type.h"
@@ -553,6 +554,84 @@ TupleDescInitEntry(TupleDesc desc,
ReleaseSysCache(tuple);
}
+/*
+ * TupleDescInitBuiltinEntry
+ * Initialize a tuple descriptor without catalog access. Only
+ * a limited range of builtin types are supported.
+ */
+void
+TupleDescInitBuiltinEntry(TupleDesc desc,
+ AttrNumber attributeNumber,
+ const char *attributeName,
+ Oid oidtypeid,
+ int32 typmod,
+ int attdim)
+{
+ Form_pg_attribute att;
+
+ /* sanity checks */
+ AssertArg(PointerIsValid(desc));
+ AssertArg(attributeNumber >= 1);
+ AssertArg(attributeNumber <= desc->natts);
+
+ /* initialize the attribute fields */
+ att = desc->attrs[attributeNumber - 1];
+ att->attrelid = 0; /* dummy value */
+
+ /* unlike TupleDescInitEntry, we require an attribute name */
+ Assert(attributeName != NULL);
+ namestrcpy(&(att->attname), attributeName);
+
+ att->attstattarget = -1;
+ att->attcacheoff = -1;
+ att->atttypmod = typmod;
+
+ att->attnum = attributeNumber;
+ att->attndims = attdim;
+
+ att->attnotnull = false;
+ att->atthasdef = false;
+ att->attisdropped = false;
+ att->attislocal = true;
+ att->attinhcount = 0;
+ /* attacl, attoptions and attfdwoptions are not present in tupledescs */
+
+ att->atttypid = oidtypeid;
+
+ /*
+ * Our goal here is to support just enough types to let basic builtin
+ * commands work without catalog access - e.g. so that we can do certain
+ * things even in processes that are not connected to a database.
+ */
+ switch (oidtypeid)
+ {
+ case TEXTOID:
+ case TEXTARRAYOID:
+ att->attlen = -1;
+ att->attbyval = false;
+ att->attalign = 'i';
+ att->attstorage = 'x';
+ att->attcollation = DEFAULT_COLLATION_OID;
+ break;
+
+ case BOOLOID:
+ att->attlen = 1;
+ att->attbyval = true;
+ att->attalign = 'c';
+ att->attstorage = 'p';
+ att->attcollation = InvalidOid;
+ break;
+
+ case INT4OID:
+ att->attlen = 4;
+ att->attbyval = true;
+ att->attalign = 'i';
+ att->attstorage = 'p';
+ att->attcollation = InvalidOid;
+ break;
+ }
+}
+
/*
* TupleDescInitEntryCollation
*
diff --git a/src/backend/replication/repl_gram.y b/src/backend/replication/repl_gram.y
index d962c76819..b35d0f0cd1 100644
--- a/src/backend/replication/repl_gram.y
+++ b/src/backend/replication/repl_gram.y
@@ -61,6 +61,7 @@ Node *replication_parse_result;
/* Keyword tokens. */
%token K_BASE_BACKUP
%token K_IDENTIFY_SYSTEM
+%token K_SHOW
%token K_START_REPLICATION
%token K_CREATE_REPLICATION_SLOT
%token K_DROP_REPLICATION_SLOT
@@ -82,14 +83,14 @@ Node *replication_parse_result;
%type command
%type base_backup start_replication start_logical_replication
create_replication_slot drop_replication_slot identify_system
- timeline_history
+ timeline_history show
%type base_backup_opt_list
%type base_backup_opt
%type opt_timeline
%type plugin_options plugin_opt_list
%type plugin_opt_elem
%type plugin_opt_arg
-%type opt_slot
+%type opt_slot var_name
%type opt_reserve_wal opt_temporary
%%
@@ -112,6 +113,7 @@ command:
| create_replication_slot
| drop_replication_slot
| timeline_history
+ | show
;
/*
@@ -124,6 +126,22 @@ identify_system:
}
;
+/*
+ * SHOW setting
+ */
+show:
+ K_SHOW var_name
+ {
+ VariableShowStmt *n = makeNode(VariableShowStmt);
+ n->name = $2;
+ $$ = (Node *) n;
+ }
+
+var_name: IDENT { $$ = $1; }
+ | var_name '.' IDENT
+ { $$ = psprintf("%s.%s", $1, $3); }
+ ;
+
/*
* BASE_BACKUP [LABEL '