Index: catalog/heap.c
===================================================================
RCS file: /home/alvherre/cvs/pgsql/src/backend/catalog/heap.c,v
retrieving revision 1.293
diff -c -r1.293 heap.c
*** catalog/heap.c	22 Nov 2005 18:17:08 -0000	1.293
--- catalog/heap.c	9 Dec 2005 16:21:09 -0000
***************
*** 2074,2076 ****
--- 2137,2202 ----
  	systable_endscan(fkeyScan);
  	heap_close(fkeyRel, AccessShareLock);
  }
+ 
+ /*
+  * Mark a relation as no longer frozen in pg_class.  We violate no-overwrite
+  * semantics here by storing the new minxid value directly into the pg_class
+  * tuple that's already in the page.  The reason for this is that our change
+  * must persist even if our transaction aborts.
+  */
+ void
+ heap_unfreeze(Relation rel)
+ {
+ 	Relation	classRel;
+ 	Form_pg_class classForm;
+ 	HeapTuple	tuple;
+ 	HeapTupleData rtup;
+ 	Oid			relid = RelationGetRelid(rel);
+ 	Buffer		buffer;
+ 
+ 	/*
+ 	 * Throw a warning due to deadlock risk.  This is not an error so we have
+ 	 * a chance to correct the bogus state and continue with the original
+ 	 * operation.  It's possible to get a deadlock below however.
+ 	 */
+ 	if (IsSystemRelation(rel))
+ 		ereport(WARNING,
+ 				(errcode(ERRCODE_WARNING),
+ 				 errmsg("system catalogs must not be marked as frozen")));
+ 
+ 	classRel = heap_open(RelationRelationId, RowExclusiveLock);
+ 
+ 	tuple = SearchSysCache(RELOID,
+ 						   ObjectIdGetDatum(relid),
+ 						   0, 0, 0);
+ 	if (!HeapTupleIsValid(tuple))
+ 		elog(ERROR, "cache lookup failed for relation %u", relid);
+ 
+ 	rtup.t_self = tuple->t_self;
+ 	ReleaseSysCache(tuple);
+ 	if (!heap_fetch(classRel, SnapshotNow, &rtup, &buffer, false, NULL))
+ 		elog(ERROR, "pg_class entry for relid %u vanished during unfreezing",
+ 			 relid);
+ 
+ 	/* Ensure no one does this at the same time */
+ 	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
+ 
+ 	classForm = (Form_pg_class) GETSTRUCT(&rtup);
+ 	classForm->relminxid = RecentXmin;
+ 
+ 	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
+ 
+ 	/*
+ 	 * Invalidate the tuple in the catcaches; this also arranges to flush
+ 	 * the relation's relcache entry.
+ 	 *
+ 	 * FIXME -- If we fail to commit for some reason, no flush will occur.
+ 	 * This is a bug.
+ 	 */
+ 	CacheInvalidateHeapTuple(classRel, &rtup);
+ 
+ 	/* Write the buffer */
+ 	WriteBuffer(buffer);
+ 
+ 	heap_close(classRel, RowExclusiveLock);
+ }
Index: parser/parse_clause.c
===================================================================
RCS file: /home/alvherre/cvs/pgsql/src/backend/parser/parse_clause.c,v
retrieving revision 1.144
diff -c -r1.144 parse_clause.c
*** parser/parse_clause.c	22 Nov 2005 18:17:16 -0000	1.144
--- parser/parse_clause.c	9 Dec 2005 15:37:02 -0000
***************
*** 157,162 ****
--- 157,168 ----
  	pstate->p_target_relation = heap_openrv(relation, RowExclusiveLock);
  
  	/*
+ 	 * If the relation is currently frozen, need to unfreeze it before use.
+ 	 */
+ 	if (pstate->p_target_relation->rd_rel->relminxid == FrozenTransactionId)
+ 		heap_unfreeze(pstate->p_target_relation);
+ 
+ 	/*
  	 * Now build an RTE.
  	 */
  	rte = addRangeTableEntryForRelation(pstate, pstate->p_target_relation,