Fix define_custom_variable so that SUSET custom variables behave

somewhat reasonably.  It's not perfect, but it beats the kluge
proposed in the auto-explain patch ...

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 3e96752..2d1babc 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.478 2008/11/19 01:10:23 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.479 2008/11/19 02:07:07 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -5657,6 +5657,7 @@ define_custom_variable(struct config_generic * variable)
        const char **nameAddr = &name;
        const char *value;
        struct config_string *pHolder;
+       GucContext phcontext;
        struct config_generic **res;
 
        /*
@@ -5703,6 +5704,28 @@ define_custom_variable(struct config_generic * variable)
        *res = variable;
 
        /*
+        * Infer context for assignment based on source of existing value.
+        * We can't tell this with exact accuracy, but we can at least do
+        * something reasonable in typical cases.
+        */
+       switch (pHolder->gen.source)
+       {
+               case PGC_S_DEFAULT:
+               case PGC_S_ENV_VAR:
+               case PGC_S_FILE:
+               case PGC_S_ARGV:
+                       phcontext = PGC_SIGHUP;
+                       break;
+               case PGC_S_DATABASE:
+               case PGC_S_USER:
+               case PGC_S_CLIENT:
+               case PGC_S_SESSION:
+               default:
+                       phcontext = PGC_USERSET;
+                       break;
+       }
+
+       /*
         * Assign the string value stored in the placeholder to the real variable.
         *
         * XXX this is not really good enough --- it should be a nontransactional
@@ -5713,7 +5736,7 @@ define_custom_variable(struct config_generic * variable)
 
        if (value)
                set_config_option(name, value,
-                                                 pHolder->gen.context, pHolder->gen.source,
+                                                 phcontext, pHolder->gen.source,
                                                  GUC_ACTION_SET, true);
 
        /*