From: Chris Browne <cbbrowne@acm.org>
To: pgsql-performance@postgresql.org
Subject: Re: Scaling up PostgreSQL in Multiple CPU / Dual Core
Date: Fri, 24 Mar 2006 14:33:21 -0500
Message-ID: <60r74rskn2.fsf@dba2.int.libertyrms.com> (raw)
References: <65f9ddfb0603222219r1742c2aevda37acd55ca845be@mail.gmail.com>
<1143131901.17999.67.camel@state.g2switchworks.com>
<4422D033.2030407@commandprompt.com>
<1143133364.17999.77.camel@state.g2switchworks.com>
<87hd5olgyd.fsf@wolfe.cbbrowne.com>
<20060324101440.GP90527@pervasive.com>
<60zmjfsnz0.fsf@dba2.int.libertyrms.com>
<20060324192122.GJ15140@mathom.us>
mstone+postgres@mathom.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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To: pgsql-performance@postgresql.org
Cc: cbbrowne@acm.org
Subject: Re: Scaling up PostgreSQL in Multiple CPU / Dual Core
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