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);