Remove ancient restriction that LIMIT/OFFSET can't contain a sub-select.

tglsfdc · tglsfdc · commit cc80f0a340cd · 2008-02-15T17:19:46.000Z
This was probably protecting some implementation limitation when it was
put in, but as far as I can tell the planner and executor have no such
assumption anymore; the case seems to work fine.  Per a gripe from
Grzegorz Jaskiewicz.
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.168 2008/01/01 19:45:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.169 2008/02/15 17:19:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1091,9 +1091,7 @@ transformLimitClause(ParseState *pstate, Node *clause,
 	qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName);
 
 	/*
-	 * LIMIT can't refer to any vars or aggregates of the current query; we
-	 * don't allow subselects either (though that case would at least be
-	 * sensible)
+	 * LIMIT can't refer to any vars or aggregates of the current query
 	 */
 	if (contain_vars_of_level(qual, 0))
 	{
@@ -1111,14 +1109,6 @@ transformLimitClause(ParseState *pstate, Node *clause,
 				 errmsg("argument of %s must not contain aggregates",
 						constructName)));
 	}
-	if (contain_subplans(qual))
-	{
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-		/* translator: %s is name of a SQL construct, eg LIMIT */
-				 errmsg("argument of %s must not contain subqueries",
-						constructName)));
-	}
 
 	return qual;
 }

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.168 2008/01/01 19:45:50 momjian Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.169 2008/02/15 17:19:46 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -1091,9 +1091,7 @@ transformLimitClause(ParseState pstate, Node clause,`
`1091`	`1091`	`qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName);`
`1092`	`1092`
`1093`	`1093`	`/*`
`1094`		`- * LIMIT can't refer to any vars or aggregates of the current query; we`
`1095`		`- * don't allow subselects either (though that case would at least be`
`1096`		`- * sensible)`
	`1094`	`+ * LIMIT can't refer to any vars or aggregates of the current query`
`1097`	`1095`	`*/`
`1098`	`1096`	`if (contain_vars_of_level(qual, 0))`
`1099`	`1097`	`{`
`@@ -1111,14 +1109,6 @@ transformLimitClause(ParseState pstate, Node clause,`
`1111`	`1109`	`errmsg("argument of %s must not contain aggregates",`
`1112`	`1110`	`constructName)));`
`1113`	`1111`	`}`
`1114`		`- if (contain_subplans(qual))`
`1115`		`- {`
`1116`		`- ereport(ERROR,`
`1117`		`- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),`
`1118`		`- /* translator: %s is name of a SQL construct, eg LIMIT */`
`1119`		`- errmsg("argument of %s must not contain subqueries",`
`1120`		`- constructName)));`
`1121`		`- }`
`1122`	`1112`
`1123`	`1113`	`return qual;`
`1124`	`1114`	`}`