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Re: Scaling up PostgreSQL in Multiple CPU / Dual Core

From: Chris Browne <cbbrowne(at)acm(dot)org>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Scaling up PostgreSQL in Multiple CPU / Dual Core
Date: 2006-03-24 19:33:21
Message-ID: 60r74rskn2.fsf@dba2.int.libertyrms.com (view raw or flat)
Thread:
Lists: pgsql-performance
mstone+postgres(at)mathom(dot)us (Michael Stone) writes:

> On Fri, Mar 24, 2006 at 01:21:23PM -0500, Chris Browne wrote:
>>A naive read on this is that you might start with one backend process,
>>which then spawns 16 more.  Each of those backends is scanning through
>>one of those 16 files; they then throw relevant tuples into shared
>>memory to be aggregated/joined by the central one.
>
> Of course, table scanning is going to be IO limited in most cases, and
> having every query spawn 16 independent IO threads is likely to slow
> things down in more cases than it speeds them up. It could work if you
> have a bunch of storage devices, but at that point it's probably
> easier and more direct to implement a clustered approach.

All stipulated, yes.  It obviously wouldn't be terribly useful to scan
more aggressively than I/O bandwidth can support.  The point is that
this is one of the kinds of places where concurrent processing could
do some good...
-- 
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