Re: Parallel Query Processing - Mailing list pgsql-general

From Raymond O'Donnell
Subject Re: Parallel Query Processing
Date
Msg-id 49D0B4F3.8040309@iol.ie
Whole thread Raw
In response to Parallel Query Processing  (aravind chandu <avin_friends@yahoo.com>)
List pgsql-general
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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