Horton

Re: [HACKERS] Slow count(*) again...

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Vitalii Tymchyshyn <tivv00@gmail.com>
Cc: Jon Nelson <jnelson+pgsql@jamponi.net>, Mladen Gogala <mladen.gogala@vmsinfo.com>, Andrew Dunstan <andrew@dunslane.net>, Bruce Momjian <bruce@momjian.us>, Tom Lane <tgl@sss.pgh.pa.us>, "david@lang.hm" <david@lang.hm>, Craig Ringer <craig@postnewspapers.com.au>, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Date: 2011-02-03T15:31:27Z
Lists: pgsql-hackers, pgsql-performance 
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