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Re: Any better plan for this query?..

From: Dimitri <dimitrik(dot)fr(at)gmail(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Aidan Van Dyk <aidan(at)highrise(dot)ca>, Merlin Moncure <mmoncure(at)gmail(dot)com>, PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Any better plan for this query?..
Date: 2009-05-18 18:00:59
Message-ID: 5482c80a0905181100m69f11a5dof8e4d6fc20c81dc8@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
Folks, I've just published a full report including all results here:
http://dimitrik.free.fr/db_STRESS_PostgreSQL_837_and_84_May2009.html

From my point of view it needs first to understand where the time is
wasted on a single query (even when the statement is prepared it runs
still slower comparing to MySQL).

Then to investigate on scalability issue I think a bigger server will
be needed here (I'm looking for 64cores at least :-))

If  you have some other ideas or patches (like Simon) - don't hesitate
to send them - once I'll get an access to the server again the
available test time will be very limited..

Best regards!
-Dimitri


On 5/18/09, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>
> On Thu, 2009-05-14 at 20:25 +0200, Dimitri wrote:
>
>> # lwlock_wait_8.4.d `pgrep -n postgres`
>
>>                Lock Id            Mode   Combined Time (ns)
>>       FirstLockMgrLock       Exclusive                 803700
>>        BufFreelistLock       Exclusive                 3001600
>>       FirstLockMgrLock          Shared               4586600
>>  FirstBufMappingLock       Exclusive              6283900
>>  FirstBufMappingLock          Shared             21792900
>
> I've published two patches to -Hackers to see if we can improve the read
> only numbers on 32+ cores.
>
> Try shared_buffer_partitions = 256
>
> --
>  Simon Riggs           www.2ndQuadrant.com
>  PostgreSQL Training, Services and Support
>
>

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