On Thursday 16 July 2009 17:27:39 Greg Stark wrote: > On Thu, Jul 16, 2009 at 4:16 PM, Tom Lane<t...@sss.pgh.pa.us> wrote: > > However, I do observe that this seems a sufficient counterexample > > against the theory that we can just remove the collapse limits and let > > GEQO save us on very complex queries. On my machine, the example query > > takes about 22 seconds to plan using CVS HEAD w/ all default settings. > > If I set both collapse_limit variables to very high values (I used 999), > > it takes ... um ... not sure; I gave up waiting after half an hour. > What's the point of GEQO if it doesn't guarantee to produce the > optimal plana and *also* doesn't guarantee to produce some plan, any > plan, within some reasonable amount of time? Either we need to fix > that or else I don't see what it's buying us over our regular planner > which also might not produce a plan within a reasonable amount of time > but at least if it does it'll be the right plan. Well, I could not find a plan where it errored out with the old limits. So one could argue its just not adapted. Although I also could not find a single case where geqo was relevantly faster with the default settings even if it was used. The default settings currently make it relatively hard to trigger geqo at all.
Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers