From: Arjen van der Meijden <acmmailing@tweakers.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: 8.2rc1 (much) slower than 8.2dev?
Date: Mon, 04 Dec 2006 17:41:14 +0100
Message-ID: <45744FAA.20603@tweakers.net> (raw)
In-Reply-To: <16696.1165244024@sss.pgh.pa.us>
References: <4573D1F7.600@tweakers.net>
<16696.1165244024@sss.pgh.pa.us>
Tom Lane wrote:
> Arjen van der Meijden <acmmailing@tweakers.net> writes:
>> I'll run another analyze on the database to see if that makes any
>> difference, but after that I'm not sure what to check first to figure
>> out where things go wrong?
>
> Look for changes in plans?
Yeah, there are a few number of small changes in plans and costs
estimated. I've a large list of queries executed against both databases,
and I haven't seen any differences in row-estimates, so the analyze's
have yielded similar enough results.
I'm not sure whether some of the changes are for better or worse, you
can probably spot that a bit faster than I can. I saw a few index scans
replaced by seq scans (on small tables), all index scans seem to have
doubled in cost? And I saw a few bitmap scans in stead of normal index
scans and more such small changes. But not so small if you execute a
hundreds of thousands of those queries.
Since I'd rather not send the entire list of queries to the entire
world, is it OK to send both explain analyze-files to you off list?
Best regards,
Arjen
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To: pgsql-performance@postgresql.org
Cc: acmmailing@tweakers.net, tgl@sss.pgh.pa.us
Subject: Re: 8.2rc1 (much) slower than 8.2dev?
In-Reply-To: <45744FAA.20603@tweakers.net>
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