| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Dimitri Fontaine <dfontaine(at)hi-media(dot)com> |
| Cc: | Greg Stark <gsstark(at)mit(dot)edu>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: *_collapse_limit, geqo_threshold |
| Date: | 2009-07-07 19:45:24 |
| Message-ID: | 26994.1246995924@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Dimitri Fontaine <dfontaine(at)hi-media(dot)com> writes:
> Another idea would be to have more complex metrics for deciding when
> to run geqo, that is guesstimate the query planning difficulty very
> quickly, based on more than just the number of relations in the from:
> presence of subqueries, UNION, EXISTS, IN, or branches in where
> clause, number of operators and index support for them, maybe some
> information from the stats too...
Pointless, since GEQO is only concerned with examining alternative join
orderings. I see no reason whatever to think that number-of-relations
isn't the correct variable to test to decide whether to use it.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Alvaro Herrera | 2009-07-07 19:59:36 | Re: Maintenance Policy? |
| Previous Message | Tom Lane | 2009-07-07 19:42:00 | Re: [HACKERS] commitfest.postgresql.org |