| From: | Michael Fuhr <mike(at)fuhr(dot)org> |
|---|---|
| To: | Daniel Gish <dan(at)centrifugesolutions(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Inconsistant query plan |
| Date: | 2006-01-24 23:58:57 |
| Message-ID: | 20060124235857.GA92385@winnie.fuhr.org |
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| Thread: | |
| Lists: | pgsql-performance |
On Tue, Jan 24, 2006 at 04:15:57PM -0700, Daniel Gish wrote:
> We are running Postgresql 8.1, and getting dramatically inconsistant results
> after running VACUUM ANALYZE. Sometimes after analyzing the database, the
> query planner chooses a very efficient plan (15 rows, 4.744 ms), and
> sometimes a terrible one (24 rows, 3536.995 ms). Here's the abbreviated
> query:
>
> SELECT * FROM t1 INNER JOIN (t2 INNER JOIN (t3 INNER JOIN t4 ON t3.gid =
> t4.gid) ON t3.gid = t2.gid) ON t2.eid = t1.eid WHERE ...
How abbreviated is that example? Are you actually joining more
tables than that? In another recent thread varying plans were
attributed to exceeding geqo_threshold:
http://archives.postgresql.org/pgsql-performance/2006-01/msg00132.php
Does your situation look similar?
--
Michael Fuhr
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