Remove heap_mark4update from AlterTableCreateToastTable. This has

never been the correct procedure for locking a relation, and the
recently-found ALTER TABLE bug with adding a constraint and a toast
table in the same command shows why it's a bad idea.

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3b06c6915b288718c10ac7932f7c4437899a0618..7b49ba720aac69408a42aa429898140dcae3cfa5 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.39 2002/09/04 20:31:15 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.40 2002/09/06 00:01:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3325,11 +3325,9 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
 {
        Relation        rel;
        HeapTuple       reltup;
-       HeapTupleData classtuple;
        TupleDesc       tupdesc;
        bool            shared_relation;
        Relation        class_rel;
-       Buffer          buffer;
        Oid                     toast_relid;
        Oid                     toast_idxid;
        char            toast_relname[NAMEDATALEN];
@@ -3366,42 +3364,14 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
        if (shared_relation && IsUnderPostmaster)
                elog(ERROR, "Shared relations cannot be toasted after initdb");
 
-       /*
-        * lock the pg_class tuple for update (is that really needed?)
-        */
-       class_rel = heap_openr(RelationRelationName, RowExclusiveLock);
-
-       reltup = SearchSysCache(RELOID,
-                                                       ObjectIdGetDatum(relOid),
-                                                       0, 0, 0);
-       if (!HeapTupleIsValid(reltup))
-               elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
-                        RelationGetRelationName(rel));
-       classtuple.t_self = reltup->t_self;
-       ReleaseSysCache(reltup);
-
-       switch (heap_mark4update(class_rel, &classtuple, &buffer,
-                                                        GetCurrentCommandId()))
-       {
-               case HeapTupleSelfUpdated:
-               case HeapTupleMayBeUpdated:
-                       break;
-               default:
-                       elog(ERROR, "couldn't lock pg_class tuple");
-       }
-       reltup = heap_copytuple(&classtuple);
-       ReleaseBuffer(buffer);
-
        /*
         * Is it already toasted?
         */
-       if (((Form_pg_class) GETSTRUCT(reltup))->reltoastrelid != InvalidOid)
+       if (rel->rd_rel->reltoastrelid != InvalidOid)
        {
                if (silent)
                {
                        heap_close(rel, NoLock);
-                       heap_close(class_rel, NoLock);
-                       heap_freetuple(reltup);
                        return;
                }
 
@@ -3417,8 +3387,6 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
                if (silent)
                {
                        heap_close(rel, NoLock);
-                       heap_close(class_rel, NoLock);
-                       heap_freetuple(reltup);
                        return;
                }
 
@@ -3509,8 +3477,17 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
        setRelhasindex(toast_relid, true, true, toast_idxid);
 
        /*
-        * Store the toast table's OID in the parent relation's tuple
+        * Store the toast table's OID in the parent relation's pg_class row
         */
+       class_rel = heap_openr(RelationRelationName, RowExclusiveLock);
+
+       reltup = SearchSysCacheCopy(RELOID,
+                                                               ObjectIdGetDatum(relOid),
+                                                               0, 0, 0);
+       if (!HeapTupleIsValid(reltup))
+               elog(ERROR, "ALTER TABLE: relation \"%s\" not found",
+                        RelationGetRelationName(rel));
+
        ((Form_pg_class) GETSTRUCT(reltup))->reltoastrelid = toast_relid;
 
        simple_heap_update(class_rel, &reltup->t_self, reltup);
@@ -3520,6 +3497,8 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
 
        heap_freetuple(reltup);
 
+       heap_close(class_rel, RowExclusiveLock);
+
        /*
         * Register dependency from the toast table to the master, so that the
         * toast table will be deleted if the master is.
@@ -3534,9 +3513,8 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
        recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
 
        /*
-        * Close relations and make changes visible
+        * Clean up and make changes visible
         */
-       heap_close(class_rel, NoLock);
        heap_close(rel, NoLock);
 
        CommandCounterIncrement();