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From: Bruce Momjian <bruce@momjian.us>
Message-Id: <200611221811.kAMIBFu08526@momjian.us>
Subject: Re: [Sequoia] PostgreSQL Documentation of High Availability
In-Reply-To: <45642C48.4030309@bluegap.ch>
To: Markus Schiltknecht <markus@bluegap.ch>
Date: Wed, 22 Nov 2006 13:11:15 -0500 (EST)
CC: Emmanuel Cecchet <emmanuel.cecchet@continuent.com>,
	pgsql-docs@postgresql.org,
	Sequoia general mailing list <sequoia@lists.forge.continuent.org>
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Markus Schiltknecht wrote:
> Hello Emmanuel,
> 
> Emmanuel Cecchet wrote:
> >>> Even here I think that there is a common misconception between 
> >>> performance and scalability. Most people think that by having 
> >>> multiple nodes their query will run faster which is obviously wrong 
> >>> if your original workload does not saturate a single node. 
> >>
> >> Sure. Do you think that should be made clearer?
> > Yes, I think so because this is a very common belief that we experience 
> > with new users.
> 
> Okay, I have forwarded that to Bruce, who's editing the documentation 
> (and is a native English speaker). I'm not sure how we can cover this, 
> as we are very general in our description.

OK, updated:

  <term>Multi-Server Parallel Query Execution</term>
  <listitem>

   <para>
    Many of the above solutions allow multiple servers to handle
    multiple queries, but none allow a single query to use multiple
    servers to complete faster.  This solution allows multiple
    servers to work concurrently on a single query.  This is usually
    accomplished by splitting the data among servers and having
    each server execute its part of the query and return results
    to a central server where they are combined and returned to
    the user.  Pgpool-II has this capability.

-- 
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +