From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Karim Nassar <karim.nassar@acm.org>
Cc: Simon Riggs <simon@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Christopher Kings-Lynne <chriskl@familyhealth.com.au>
Cc: pgsql-performance@postgresql.org
Subject: Re: Delete query takes exorbitant amount of time
Date: Sat, 26 Mar 2005 15:18:16 -0800 (PST)
Message-ID: <20050326151658.D82144@megazone.bigpanda.com> (raw)
In-Reply-To: <1111865788.9172.13.camel@k2.cet.nau.edu>
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On Sat, 26 Mar 2005, Karim Nassar wrote:
> On Sat, 2005-03-26 at 07:55 -0800, Stephan Szabo wrote:
> > That seems like it should be okay, hmm, what does something like:
> >
> > PREPARE test(int) AS SELECT 1 from measurement where
> > id_int_sensor_meas_type = $1 FOR UPDATE;
> > EXPLAIN ANALYZE EXECUTE TEST(1);
> >
> > give you as the plan?
>
> QUERY PLAN
> -----------------------------------------------------------------------------------------------------------------------
> Seq Scan on measurement (cost=0.00..164559.16 rows=509478 width=6)
> (actual time=11608.402..11608.402 rows=0 loops=1)
> Filter: (id_int_sensor_meas_type = $1)
> Total runtime: 11608.441 ms
> (3 rows)
Hmm, has measurement been analyzed recently? You might want to see if
raising the statistics target on measurement.id_int_sensor_meas_type and
reanalyzing changes the estimated rows down from 500k.
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To: pgsql-performance@postgresql.org
Cc: sszabo@megazone.bigpanda.com, karim.nassar@acm.org, simon@2ndquadrant.com, tgl@sss.pgh.pa.us, chriskl@familyhealth.com.au
Subject: Re: Delete query takes exorbitant amount of time
In-Reply-To: <20050326151658.D82144@megazone.bigpanda.com>
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