| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | david(at)lang(dot)hm |
| Cc: | Vitalii Tymchyshyn <tivv00(at)gmail(dot)com>, Kenneth Marshall <ktm(at)rice(dot)edu>, Jon Nelson <jnelson+pgsql(at)jamponi(dot)net>, 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>, 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: | 2011-02-05 06:37:49 |
| Message-ID: | AANLkTi=EkCUkQs9VTtW4aOBNNNV0gi8jYZhNgdHuFTKM@mail.gmail.com |
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| Lists: | pgsql-hackers pgsql-performance |
On Sat, Feb 5, 2011 at 12:46 AM, <david(at)lang(dot)hm> wrote:
>> Actually for me the main "con" with streaming analyze is that it adds
>> significant CPU burden to already not too fast load process. Especially if
>> it's automatically done for any load operation performed (and I can't see
>> how it can be enabled on some threshold).
>
> two thoughts
>
> 1. if it's a large enough load, itsn't it I/O bound?
Sometimes. Our COPY is not as cheap as we'd like it to be.
> 2. this chould be done in a separate process/thread than the load itself,
> that way the overhead of the load is just copying the data in memory to the
> other process.
I think that's more expensive than you're giving it credit for.
But by all means implement it and post the patch if it works out...!
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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