Parallel Query Processing

Thanks for your reply guys.My aim is to run multiple queries.Will joins come under multiple queries? or it just mean two or more different queries like one select statement and another select statement? Does postgresql itself supports to run multiple queries or we have to use pgpool-II tool?

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From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: aravind chandu <avin_friends(at)yahoo(dot)com>
Cc: postgresql Forums <pgsql-general(at)postgresql(dot)org>
Sent: Wednesday, March 25, 2009 4:52:43 PM
Subject: Re: [GENERAL] Parallel Query Processing

On Wed, Mar 25, 2009 at 2:24 PM, aravind chandu <avin_friends(at)yahoo(dot)com> wrote:
> Hello,
>
> I have a few questions related to the parallel query
> processing.Can you guys tell me how to implement parallel query processing
> in postgresql database.

Do you mean one query being parallelized, or multiple queries running at once?

PostgreSQL provides no capability to parallelize one query into
multiple processes.

Multiple Queries run in parallel automatically
Hello,

On 30/03/2009 07:18, aravind chandu wrote:

> Thanks for your reply guys.My aim is to run multiple queries.Will
> joins come under multiple queries? or it just mean two or more

Not sure what you're getting at here....a query that includes a JOIN is
still one query.

> different queries like one select statement and another select
> statement? Does postgresql itself supports to run multiple queries or
> we have to use pgpool-II tool?

PostgreSQL spawns a new process for each connection, and runs these in
parallel. Within each connection, a client can run as many queries as it
likes; and these are going on at the same time as queries in other
connections.

You should read the part of the docs that talks about MVCC to understand
how each process sees its own snapshot of the data.

Ray.

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