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the default_statistics_target is set to 200, and I have run the analyze and reindex on these tables before writing the email.
Andrew > Date: Tue, 5 Jun 2012 08:15:45 -0500 > From: sthomas@xxxxxxxxxxxxxxxx > To: andrewjaimes@xxxxxxxxxxx > CC: pgsql-performance@xxxxxxxxxxxxxx > Subject: Re: Sequencial scan in a JOIN > > On 06/05/2012 07:48 AM, Andrew Jaimes wrote: > > > ' -> Hash Join (cost=10.93..99795.09 rows=242803 width=0) (actual > > time=0.541..2249.027 rows=33 loops=1)' > > ' Hash Cond: ((a_activity.activequeueid = l_userqueue.queueid) > > AND (a_activity.sbuid = e_usersessions.sbuid))' > > ' -> Seq Scan on a_activity (cost=0.00..88462.52 rows=1208167 > > width=22) (actual time=0.010..1662.142 > > I'd be willing to bet your stats are way, way off. It expected 242,803 > rows in the hash, but only got 33. In that kind of scenario, I could > easily see the planner choosing a sequence scan over an index scan, as > doing that many index seeks would be much more expensive than scanning > the table. > > What's your default_statistics_target, and when is the last time you > analyzed the tables in this query? > > -- > Shaun Thomas > OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604 > 312-444-8534 > sthomas@xxxxxxxxxxxxxxxx > > ______________________________________________ > > See http://www.peak6.com/email_disclaimer/ for terms and conditions related to this email > > -- > Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance |
