| From: | Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com> |
|---|---|
| To: | Robert Davis <robert(at)faithwestinc(dot)com> |
| Cc: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: explain analyze results are different for each iteration |
| Date: | 2004-09-15 02:07:17 |
| Message-ID: | 20040914190607.Y35716@megazone.bigpanda.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-sql |
On Tue, 14 Sep 2004, Robert Davis wrote:
> I'm trying to benchmark some complex sql queries. One query, in
> particular, is causing problems -- its cost values can vary from 228
> to 907, its Total Runtimes from 60 ms to 5176 ms. The query plans
> show that the optimizer is choosing different plans for different
> iterations of the same query. Does anyone have any idea what's
> going on here or maybe how I can force Postgres to prefer the faster
> plan?
>
> The query plans are very long (11 tables joined) but I can include
> them if it might help. Thanks for any advice,
11 tables. You might want to see if raising geqo_threshold stabilizes the
plans since IIRC that's the threshold for using the genetic optimizer.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Iain | 2004-09-15 03:03:30 | implementing an out-of-transaction trigger |
| Previous Message | Gregory S. Williamson | 2004-09-15 01:33:11 | Re: explain analyze results are different for each iteration |