From 9f910a3b9aeab5a79142860eea53747c1f321aa3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 6 Jan 2009 02:01:27 +0000
Subject: [PATCH] Add some comments about why function parameter default
expressions are restricted.
---
src/backend/commands/functioncmds.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 91b65b3a58e..a813fd9a028 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.106 2009/01/01 17:23:38 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.107 2009/01/06 02:01:27 tgl Exp $
*
* DESCRIPTION
* These routines take the parse tree and pick out the
@@ -311,7 +311,15 @@ examine_parameter_list(List *parameters, Oid languageOid,
errmsg("cannot use table references in parameter default value")));
/*
+ * It can't return a set either --- but coerce_to_specific_type
+ * already checked that for us.
+ *
* No subplans or aggregates, either...
+ *
+ * Note: the point of these restrictions is to ensure that an
+ * expression that, on its face, hasn't got subplans, aggregates,
+ * etc cannot suddenly have them after function default arguments
+ * are inserted.
*/
if (pstate->p_hasSubLinks)
ereport(ERROR,
--
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