From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 2 Apr 2009 01:16:25 +0000 (+0000)
Subject: plpgsql's exec_simple_cast_value() mistakenly supposed that it could bypass
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=8b8b0138521c134d1ac53ac1fd889e1eb3d893b6;p=users%2Fbernd%2Fpostgres.git

plpgsql's exec_simple_cast_value() mistakenly supposed that it could bypass
casting effort whenever the input value was NULL.  However this prevents
application of not-null domain constraints in the cases that use this
function, as illustrated in bug #4741.  Since this function isn't meant
for use in performance-critical paths anyway, this certainly seems like
another case of "premature optimization is the root of all evil".

Back-patch as far as 8.2; older versions made no effort to enforce
domain constraints here anyway.
---

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index ca4f33e103..81c71e6c80 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -4351,26 +4351,23 @@ exec_simple_cast_value(Datum value, Oid valtype,
 					   Oid reqtype, int32 reqtypmod,
 					   bool isnull)
 {
-	if (!isnull)
+	if (valtype != reqtype || reqtypmod != -1)
 	{
-		if (valtype != reqtype || reqtypmod != -1)
-		{
-			Oid			typinput;
-			Oid			typioparam;
-			FmgrInfo	finfo_input;
+		Oid			typinput;
+		Oid			typioparam;
+		FmgrInfo	finfo_input;
 
-			getTypeInputInfo(reqtype, &typinput, &typioparam);
+		getTypeInputInfo(reqtype, &typinput, &typioparam);
 
-			fmgr_info(typinput, &finfo_input);
+		fmgr_info(typinput, &finfo_input);
 
-			value = exec_cast_value(value,
-									valtype,
-									reqtype,
-									&finfo_input,
-									typioparam,
-									reqtypmod,
-									isnull);
-		}
+		value = exec_cast_value(value,
+								valtype,
+								reqtype,
+								&finfo_input,
+								typioparam,
+								reqtypmod,
+								isnull);
 	}
 
 	return value;