Re: BUG #7602: Select with many joins against the same table is very slow compared to 9.2.0.

From: Craig Ringer <ringerc(at)ringerc(dot)id(dot)au>
To: daniel(dot)heden(at)sweco(dot)se
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #7602: Select with many joins against the same table is very slow compared to 9.2.0.
Date: 2012-10-16 02:30:31
Message-ID: 507CC6C7.6060200@ringerc.id.au
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On 10/15/2012 06:55 PM, daniel(dot)heden(at)sweco(dot)se wrote:
> The following bug has been logged on the website:
>
> Bug reference: 7602
> Logged by: Daniel Hedén
> Email address: daniel(dot)heden(at)sweco(dot)se
> PostgreSQL version: 9.2.1
> Operating system: Windows 7 / Vista 64-Bit
> Description:
>
> Select with many joins against the same table is very slow compared to
> 9.2.0.
> In my case 16 times, this query takes a second max on 9.2.0 but on 9.2.1 it
> takes more than 30 minutes.

Could you have accidentally reset `join_collapse_limit` to its default
value?

Show `EXPLAIN ANALYZE` output for both old and new cases, if possible.
At least for the new one.

(Please reply to the mailing list, not to me).

--
Craig Ringer

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