From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
To: pgsql-performance@postgresql.org
Cc: kaloyan@digsys.bg
Subject: Re: Slow query after upgrade from 8.2 to 8.4
Date: Wed, 14 Dec 2011 11:13:03 +1300
Message-ID: <4EE7CDEF.1040709@catalyst.net.nz> (raw)
In-Reply-To: <27472.1323444617@sss.pgh.pa.us>
References: <4EE0F3F4.8040909@digsys.bg>
<14557.1323401295@sss.pgh.pa.us>
<4EE1FDC7.70601@digsys.bg>
<27472.1323444617@sss.pgh.pa.us>
On 10/12/11 04:30, Tom Lane wrote:
> However, it's not apparent to me why you would see any difference
> between 8.2 and 8.4 on this type of query. I tried a query analogous
> to this one on both, and got identical plans. I'm guessing that your
> slowdown is due to not having updated statistics on the new
> installation, or perhaps failing to duplicate some relevant settings.
I notice he has 8.4.*8*... I wonder if he's running into the poor
estimation bug for sub-selects/semi joins that was fixed in 8.4.9.
Kaloyan, can you try the query in 8.4.9?
regards
Mark
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To: pgsql-performance@postgresql.org
Cc: mark.kirkwood@catalyst.net.nz, kaloyan@digsys.bg
Subject: Re: Slow query after upgrade from 8.2 to 8.4
In-Reply-To: <4EE7CDEF.1040709@catalyst.net.nz>
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