Avoid unnecessary fetch from pg_shadow in the normal case in

pg_class_aclmask().  We only need to do this when we have to check
pg_shadow.usecatupd, and that's not relevant unless the target table
is a system catalog.  So we can usually avoid one syscache lookup.

diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index dba7beee2677122ba632091fa6b81f39f946c6d0..5eba84f995fddcd497abc477c622e756334afc9e 100644 (file)
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/catalog/aclchk.c,v 1.111 2005/04/14 20:03:23 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/catalog/aclchk.c,v 1.112 2005/05/29 23:38:05 tgl Exp $
  *
  * NOTES
  *   See acl.h.
@@ -1310,6 +1310,29 @@ aclcheck_error(AclResult aclerr, AclObjectKind objectkind,
 }
 
 
+/* Check if given userid has usecatupd privilege according to pg_shadow */
+static bool
+has_usecatupd(AclId userid)
+{
+   bool        usecatupd;
+   HeapTuple   tuple;
+
+   tuple = SearchSysCache(SHADOWSYSID,
+                          ObjectIdGetDatum(userid),
+                          0, 0, 0);
+   if (!HeapTupleIsValid(tuple))
+       ereport(ERROR,
+               (errcode(ERRCODE_UNDEFINED_OBJECT),
+                errmsg("user with ID %u does not exist", userid)));
+
+   usecatupd = ((Form_pg_shadow) GETSTRUCT(tuple))->usecatupd;
+
+   ReleaseSysCache(tuple);
+
+   return usecatupd;
+}
+
+
 /*
  * Exported routine for examining a user's privileges for a table
  *
@@ -1325,8 +1348,6 @@ pg_class_aclmask(Oid table_oid, AclId userid,
                 AclMode mask, AclMaskHow how)
 {
    AclMode     result;
-   bool        usesuper,
-               usecatupd;
    HeapTuple   tuple;
    Form_pg_class classForm;
    Datum       aclDatum;
@@ -1335,24 +1356,7 @@ pg_class_aclmask(Oid table_oid, AclId userid,
    AclId       ownerId;
 
    /*
-    * Validate userid, find out if he is superuser, also get usecatupd
-    */
-   tuple = SearchSysCache(SHADOWSYSID,
-                          ObjectIdGetDatum(userid),
-                          0, 0, 0);
-   if (!HeapTupleIsValid(tuple))
-       ereport(ERROR,
-               (errcode(ERRCODE_UNDEFINED_OBJECT),
-                errmsg("user with ID %u does not exist", userid)));
-
-   usecatupd = ((Form_pg_shadow) GETSTRUCT(tuple))->usecatupd;
-
-   ReleaseSysCache(tuple);
-
-   usesuper = superuser_arg(userid);
-
-   /*
-    * Now get the relation's tuple from pg_class
+    * Must get the relation's tuple from pg_class
     */
    tuple = SearchSysCache(RELOID,
                           ObjectIdGetDatum(table_oid),
@@ -1377,7 +1381,7 @@ pg_class_aclmask(Oid table_oid, AclId userid,
    if ((mask & (ACL_INSERT | ACL_UPDATE | ACL_DELETE)) &&
        IsSystemClass(classForm) &&
        classForm->relkind != RELKIND_VIEW &&
-       !usecatupd &&
+       !has_usecatupd(userid) &&
        !allowSystemTableMods)
    {
 #ifdef ACLDEBUG
@@ -1389,7 +1393,7 @@ pg_class_aclmask(Oid table_oid, AclId userid,
    /*
     * Otherwise, superusers bypass all permission-checking.
     */
-   if (usesuper)
+   if (superuser_arg(userid))
    {
 #ifdef ACLDEBUG
        elog(DEBUG2, "%u is superuser, home free", userid);