Stefan Kaltenbrunner <stefan@xxxxxxxxxxxxxxxx> writes: > Julius Stroffek wrote: >> There is a proposal attached to this mail about the interface >> we would like to implement for switching between different >> optimizers. Please review it and provide a feedback to us. > hmm - how does is that proposal different from what got implemented with: > http://archives.postgresql.org/pgsql-committers/2007-05/msg00315.php Well, it's a very different level of abstraction. The planner_hook would allow you to replace the *entire* planner, but if you only want to replace GEQO (that is, only substitute some other heuristics for partial search of a large join-order space), doing it from planner_hook will probably require duplicating a great deal of code. A hook right at the place where we currently choose "geqo or regular" would be a lot easier to experiment with. Replacing GEQO sounds like a fine area for investigation to me; I've always been dubious about whether it's doing a good job. But I'd prefer a simple hook function pointer designed in the same style as planner_hook (ie, intended to be overridden by a loadable module). The proposed addition of a system catalog and SQL-level management commands sounds like a great way to waste a lot of effort on mere decoration, before ever getting to the point of being able to demonstrate that there's any value in it. Also, while we might accept a small hook-function patch for 8.3, there's zero chance of any of that other stuff making it into this release cycle. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
