From: Robert Haas <robertmhaas@gmail.com>
To: Vitalii Tymchyshyn <tivv00@gmail.com>
Cc: Jon Nelson <jnelson+pgsql@jamponi.net>
Cc: Mladen Gogala <mladen.gogala@vmsinfo.com>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: david@lang.hm <david@lang.hm>
Cc: Craig Ringer <craig@postnewspapers.com.au>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: [HACKERS] Slow count(*) again...
Date: Thu, 3 Feb 2011 10:31:27 -0500
Message-ID: <AANLkTim0AbX71fPTOQa++q9PAGn7SL2ziYpRnb_JMyNR@mail.gmail.com> (raw)
In-Reply-To: <4D4A7B69.2020704@gmail.com>
References: <201102012247.p11Ml6u02682@momjian.us>
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<4D489AD1.1010105@vmsinfo.com>
<AANLkTiknZi97dDwm7sHqy0EL7tpNEP9sY5uPV6AN+q=u@mail.gmail.com>
<4D499E55.4020107@vmsinfo.com>
<AANLkTimo2J-BagObs_V1bGaHOO9qL+kTF6s6-wZ=M3KW@mail.gmail.com>
<AANLkTin7A_Q=Yc9Wf_5=POp2mVqmaiwqUDsFMLG68H45@mail.gmail.com>
<4D4A7B69.2020704@gmail.com>
On Thu, Feb 3, 2011 at 4:54 AM, Vitalii Tymchyshyn <tivv00@gmail.com> wrote:
> 02.02.11 20:32, Robert Haas написав(ла):
>>
>> Yeah. Any kind of bulk load into an empty table can be a problem,
>> even if it's not temporary. When you load a bunch of data and then
>> immediately plan a query against it, autoanalyze hasn't had a chance
>> to do its thing yet, so sometimes you get a lousy plan.
>
> May be introducing something like 'AutoAnalyze' threshold will help? I mean
> that any insert/update/delete statement that changes more then x% of table
> (and no less then y records) must do analyze right after it was finished.
> Defaults like x=50 y=10000 should be quite good as for me.
That would actually be a pessimization for many real world cases. Consider:
COPY
COPY
COPY
COPY
COPY
COPY
COPY
COPY
COPY
COPY
COPY
COPY
COPY
SELECT
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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Subject: Re: [HACKERS] Slow count(*) again...
In-Reply-To: <AANLkTim0AbX71fPTOQa++q9PAGn7SL2ziYpRnb_JMyNR@mail.gmail.com>
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