Robert Haas <robertmhaas@xxxxxxxxx> writes: > Yeah, I'm not familiar with the logic in that area of the code, so I > can't comment all that intelligently. However, I feel like there's a > class of things that could potentially be optimized if we know that > the only snapshot they could affect is the one we're currently using. Yeah, perhaps. The other thing I noticed while looking at the code is that CREATE INDEX's test to see whether there are broken HOT chains is borderline brain-dead: if there are any recently-dead HOT-updated tuples in the table, it assumes they represent broken HOT chains, whether they really do or not. In principle you could find the live member of the chain and see whether or not it is really different from the dead member in the columns used by the new index. In Jon's example that would win because his update didn't actually change the indexed column. It's unclear though that it would be useful often enough to be worth the extra code and cycles. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
