Re: Slow query after upgrade from 8.2 to 8.4

From: Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
To: pgsql-performance(at)postgresql(dot)org
Cc: kaloyan(at)digsys(dot)bg
Subject: Re: Slow query after upgrade from 8.2 to 8.4
Date: 2011-12-13 22:13:03
Message-ID: 4EE7CDEF.1040709@catalyst.net.nz
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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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