This is in a sense a followup to my post with subject "Wildly erratic query performance". The more I think about it the only thing that makes sense of my results is if the query planner really WAS choosing my join order truly randomly each time. I went digging into the manual and Section 49.3.1. "Generating Possible Plans with GEQO" says "In the initial stage, the GEQO code simply generates some possible join sequences at random." Now ordinarily I would interpret this use of the word "random" loosely, to mean "arbitrarily" or "using some non-meaningful selection criteria". But given what I am seeing, this leads me to consider that "random" is meant literally, and that it actually uses a random number generator to choose paths. Can someone confirm that this really is the case? If so, I is this really a good idea? Is non-deterministic behavior really acceptable? I would think it would be much more sensible to have it operate deterministically (such as with some predetermined random sequence of numbers used repeatedly). Eric -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
