From: Tom Lane <tgl@sss.pgh.pa.us>
To: Marc Cousin <cousinmarc@gmail.com>
Cc: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: inheritance: planning time vs children number vs column number
Date: Tue, 01 Mar 2011 10:33:51 -0500
Message-ID: <17604.1298993631@sss.pgh.pa.us> (raw)
In-Reply-To: <201103010842.42128.cousinmarc@gmail.com>
References: <201102281038.04945.cousinmarc@gmail.com>
<201102281947.46590.cousinmarc@gmail.com>
<4188.1298960419@sss.pgh.pa.us>
<201103010842.42128.cousinmarc@gmail.com>
Marc Cousin <cousinmarc@gmail.com> writes:
> Le mardi 01 mars 2011 07:20:19, Tom Lane a écrit :
>> It's worth pointing out that the only reason this effect is dominating
>> the runtime is that you don't have any statistics for these toy test
>> tables. If you did, the cycles spent using those entries would dwarf
>> the lookup costs, I think. So it's hard to get excited about doing
>> anything based on this test case --- it's likely the bottleneck would be
>> somewhere else entirely if you'd bothered to load up some data.
> Yes, for the same test case, with a bit of data in every partition and
> statistics up to date, planning time goes from 20 seconds to 125ms for the 600
> children/1000 columns case. Which is of course more than acceptable.
[ scratches head ... ] Actually, I was expecting the runtime to go up
not down. Maybe there's something else strange going on here.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, cousinmarc@gmail.com, heikki.linnakangas@enterprisedb.com
Subject: Re: inheritance: planning time vs children number vs column number
In-Reply-To: <17604.1298993631@sss.pgh.pa.us>
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