Robert Haas <robertmhaas@xxxxxxxxx> writes: > If at least one column in the subselect is strict, you can rewrite it > that way yourself, but the optimizer won't do it. I wish it did, but I > don't wish it badly enough to have written the code myself, and > apparently neither does anyone else. I was thinking about this earlier today. It's a bit of a PITA because we need the information very early in the planner, before it's done much analysis. So for example we might find ourselves duplicating the work that will happen later to determine which tables are nullable by outer joins. I think this would be all right as long as we ensure that it's only done when there's a chance for a win (ie, no extra cycles if there's not actually a NOT IN present). It could still be an unpleasantly large amount of new code though. Wouldn't we need to enforce that *all* columns of the subselect are non-null, rather than *any*? 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
