Re: amount of join's and sequential access to the tables involved

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From: Gerardo Herzig <gherzig@fmed.uba.ar>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-sql@postgresql.org
Subject: Re: amount of join's and sequential access to the tables involved
Date: Thu, 12 Jan 2012 11:09:55 -0300
Message-ID: <1326377395.1877.1.camel@inca.fmed.uba.ar> (raw)
In-Reply-To: <20152.1326296428@sss.pgh.pa.us>
References: <1326296192.24629.12.camel@inca.fmed.uba.ar>
	<20152.1326296428@sss.pgh.pa.us>

El mié, 11-01-2012 a las 10:40 -0500, Tom Lane escribió:
> Gerardo Herzig <gherzig@fmed.uba.ar> writes:
> > Hi all. Im working on a 'simple' query with 7, 8 left joins. After the
> > 9nth join or so, explain analyze became to show the plan with many
> > tables being read in sequential fashion. Of course, this slows down the
> > query response in a factor on 10.
> 
> increase join_collapse_limit, perhaps?
> 
> 			regards, tom lane
> 

Im sory Tom and all, again stuck with this. Now i have 9 joins, and
join_collapse_limit = 20, and the query slows down big time when the 9th
join appears.

Another configuration variable to check against?

Thanks again.
Gerardo

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