On Sun, Dec 20, 2009 at 2:11 AM, Robert Haas <robertmhaas@xxxxxxxxx> wrote: > On Fri, Dec 18, 2009 at 12:29 PM, Greg Stark <gsstark@xxxxxxx> wrote: >> A word of warning, in my experience the hardest part for changes like >> this isn't the executor changes (which in this case wouldn't be far >> from easy) but the planner changes to detect when this new plan would >> be better. > > There's also the problem of making the visibility map crash-safe. I > think I heard you might have some ideas on that one - has it been > discussed on -hackers? Not sure what ideas you mean. In the original poster's plan that isn't an issue. We could scan the index, perform the joins and restriction clauses, and only check the visibility on the resulting tuples which slip through them all. That would be possible even without crash-safe visibility bits. -- greg -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
