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From: Joshua D. Drake <jd@commandprompt.com>
To: Ben <midfield@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: partitioning question 1
Date: Thu, 28 Oct 2010 13:48:32 -0700
Message-ID: <1288298912.22359.46.camel@jd-desktop> (raw)
In-Reply-To: <73315FB7-240B-480C-9200-D547BCA942DE@gmail.com>
References: <A9A748D8-A52F-4C16-A303-3A4AA1EC1BD2@gmail.com>
	<1288287092.22359.23.camel@jd-desktop>
	<E03148FE-26C6-47BA-9463-B97749BE3E8C@gmail.com>
	<1288291814.22359.31.camel@jd-desktop>
	<4486C61F-DC08-4DE4-8AF9-245FA60B0310@gmail.com>
	<1288295052.22359.35.camel@jd-desktop>
	<73315FB7-240B-480C-9200-D547BCA942DE@gmail.com>

On Thu, 2010-10-28 at 12:59 -0700, Ben wrote:
> On Oct 28, 2010, at 12:44 PM, Joshua D. Drake wrote:
> > 
> > My tests show you are incorrect:
> > 
> > 
> > part_test=# explain analyze select * from foo join bar using (i) where
> > i=9;
> >                                                    QUERY
> > PLAN                                                    
> > ------------------------------------------------------------------------------------------------------------------
> > Nested Loop  (cost=34.26..106.76 rows=200 width=20) (actual
> > time=0.004..0.004 rows=0 loops=1)
> >   ->  Append  (cost=0.00..68.50 rows=20 width=12) (actual
> > time=0.004..0.004 rows=0 loops=1)
> >         ->  Seq Scan on foo  (cost=0.00..34.25 rows=10 width=12)
> > (actual time=0.001..0.001 rows=0 loops=1)
> >               Filter: (i = 9)
> >         ->  Seq Scan on foo_1 foo  (cost=0.00..34.25 rows=10 width=12)
> > (actual time=0.000..0.000 rows=0 loops=1)
> >               Filter: (i = 9)
> >   ->  Materialize  (cost=34.26..34.36 rows=10 width=12) (never
> > executed)
> >         ->  Seq Scan on bar  (cost=0.00..34.25 rows=10 width=12) (never
> > executed)
> >               Filter: (i = 9)
> > Total runtime: 0.032 ms
> > (10 rows)
> 
> strange.  my tests don't agree with your tests :

Do you have constraint_exclusion turned on? You should verify with show
constraint_exclusion (I saw what you wrote below).

JD

P.S. Blatant plug, you coming to http://www.postgresqlconference.org ?


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