It strikes me that CLUSTER has been broken since CREATE INDEX CONCURRENTLY was put in, because it doesn't check whether the index it's been asked to cluster on is valid. If C.I.C. fails before marking the index indisvalid, a subsequent CLUSTER would happily cluster using only the index entries that are present, thereby losing data.
Fixing this in 8.2 seems a simple matter of checking indisvalid. However I'm not quite sure what to do in HEAD: is it important to honor indcheckxmin? Offhand it seems the worst problem we could have with a not-quite-ready index is that some recently dead tuples might be scanned out-of-order because they'd be visited via a broken HOT chain; and we need not worry too much about whether CLUSTER preserves exact index ordering for such tuples. Are there any other utility commands besides CLUSTER that should be checking index validity? I don't see anything in a quick look, but maybe I missed something. Comments? regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq