From: Tom Lane <tgl@sss.pgh.pa.us>
To: Christoph Berg <christoph.berg@credativ.de>
Cc: PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1
Date: Mon, 06 May 2013 12:38:48 -0400
Message-ID: <1583.1367858328@sss.pgh.pa.us> (raw)
In-Reply-To: <20130430112055.GA27525@msgid.df7cb.de>
References: <20130430112055.GA27525@msgid.df7cb.de>
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Christoph Berg <christoph.berg@credativ.de> writes:
> We recently (finally) migrated an Request Tracker 3.4 database running
> on 8.1.19 to 9.2.4. The queries used by rt3.4 are sometimes weird, but
> 8.1 coped without too much tuning. The schema looks like this:
The newer rowcount estimates are much further away from reality:
> Unique (cost=1117.67..1118.46 rows=9 width=1115) (actual time=82.646..85.695 rows=439 loops=1)
> Unique (cost=784205.94..796940.08 rows=145533 width=1061) (actual time=9710.683..9713.175 rows=439 loops=1)
Has the new DB been analyzed? Maybe you had custom stats targets in
the old DB that didn't get copied to the new one?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, christoph.berg@credativ.de
Subject: Re: RT3.4 query needed a lot more tuning with 9.2 than it did with 8.1
In-Reply-To: <1583.1367858328@sss.pgh.pa.us>
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