Disallow CLUSTER using an invalid index (that is, one left over from a failed

CREATE INDEX CONCURRENTLY).  Such an index might not have entries for every
heap row and thus clustering with it would result in silent data loss.
The scenario requires a pretty foolish DBA, but still ...

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index d781f79..736e748 100644 (file)
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.163 2007/09/10 21:59:37 alvherre Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.164 2007/09/29 18:05:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -422,6 +422,20 @@ check_index_is_clusterable(Relation OldHeap, Oid indexOid, bool recheck)
        }
 
        /*
+        * Disallow if index is left over from a failed CREATE INDEX CONCURRENTLY;
+        * it might well not contain entries for every heap row, or might not even
+        * be internally consistent.  (But note that we don't check indcheckxmin;
+        * the worst consequence of following broken HOT chains would be that we
+        * might put recently-dead tuples out-of-order in the new table, and there
+        * is little harm in that.)
+        */
+       if (!OldIndex->rd_index->indisvalid)
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("cannot cluster on invalid index \"%s\"",
+                                               RelationGetRelationName(OldIndex))));
+
+       /*
         * Disallow clustering system relations.  This will definitely NOT work
         * for shared relations (we have no way to update pg_class rows in other
         * databases), nor for nailed-in-cache relations (the relfilenode values