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 f4f39777f0f2e8a88feaa9613776ef356c7257c6..6c86ecc5ce09c402a7e9050c361ab14fa34bb5ff 100644 (file)
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -417,6 +417,16 @@ check_index_is_clusterable(Relation OldHeap, Oid indexOid, bool recheck)
                                                        RelationGetRelationName(OldIndex))));
        }
 
+       /*
+        * Disallow if index is left over from a failed CREATE INDEX CONCURRENTLY;
+        * it might well not contain entries for every heap row.
+        */
+       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