| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Vitalii Tymchyshyn <tivv00(at)gmail(dot)com> |
| Cc: | Jon Nelson <jnelson+pgsql(at)jamponi(dot)net>, Mladen Gogala <mladen(dot)gogala(at)vmsinfo(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "david(at)lang(dot)hm" <david(at)lang(dot)hm>, Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Slow count(*) again... |
| Date: | 2011-02-03 15:31:27 |
| Message-ID: | AANLkTim0AbX71fPTOQa++q9PAGn7SL2ziYpRnb_JMyNR@mail.gmail.com |
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| Lists: | pgsql-hackers pgsql-performance |
On Thu, Feb 3, 2011 at 4:54 AM, Vitalii Tymchyshyn <tivv00(at)gmail(dot)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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