Re: Inconsistant query plan - Mailing list pgsql-performance

From Michael Fuhr
Subject Re: Inconsistant query plan
Date
Msg-id 20060124235857.GA92385@winnie.fuhr.org
Whole thread Raw
In response to Inconsistant query plan  ("Daniel Gish")
Responses Re: Inconsistant query plan  ("Daniel Gish")
List 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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