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Re: PG planning randomly ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Laurent Raufaste" <analogue(at)glop(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: PG planning randomly ?
Date: 2008-02-26 17:59:39
Message-ID: 5296.1204048779@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Laurent Raufaste" <analogue(at)glop(dot)org> writes:
> 2008/2/26, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> If it's 8.2 or later then increasing the stats target for _comment.path
>> to 100 or more would likely help.

> I'm using PG 8.2.4.
> We are using 100 as default_statistics_target by default and all our
> column are using this value:

Hmm, that ought to be enough to activate the better selectivity
estimator.

Unless ... did you update this database from a pre-8.2 DB that already
had contrib/ltree in it?  If so, did you just load the existing old
definition of ltree as part of your dump, or did you install 8.2's
version fresh?  I'm wondering if you have a definition of operator <@
that doesn't specify the new selectivity estimator.  Please try a
pg_dump -s and see what it shows as the definition of <@.

			regards, tom lane

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Subject: Re: PG planning randomly ?
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