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Re: Parallel queries slow

From: DA Morgan <damorgan_at_psoug.org>
Date: Thu, 22 Dec 2005 13:30:01 -0800
Message-ID: <1135286985.846822@jetspin.drizzle.com>


Marek Läll wrote:
> Hi,
>

>> The problem: When I execute a query it takes about 3 seconds when
>> executing it in parallel. When I specify the hint NOPARALLEL it takes
>> only about 0.2 secs.

>
>
> If your query (in noparallel mode) takes less than ~10 minutes then
> forget everything about parallel queries.
> Allocating slaves AND shareing work between slaves AND exchangeing
> results between slaves AND finally merging results for serial user is
> very expensive task.
>
>
> regards,
> marek.

Quite possibly something similar to a project I worked on a few years back where someone thought 8 full table scans would be faster than one.

-- 
Daniel A. Morgan
http://www.psoug.org
damorgan_at_x.washington.edu
(replace x with u to respond)
Received on Thu Dec 22 2005 - 15:30:01 CST

Original text of this message

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