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 573d293f4ccfce01e4f4834eee58220104399c5e..c6658fca357ea98ef1beec4f61d6de0418240e84 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.236 2009/03/26 22:26:08 petere Exp $
+ *       $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.237 2009/04/02 01:16:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -4754,26 +4754,23 @@ 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;