From: Tom Lane <tgl@sss.pgh.pa.us>
To: grant@amadensor.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Fun little performance IMPROVEMENT...
Date: Fri, 21 Jan 2011 14:50:47 -0500
Message-ID: <17636.1295639447@sss.pgh.pa.us> (raw)
In-Reply-To: <fb95011e666ffd6528d0b57542d7097f.squirrel@grant.boldlygoingnowhere.org>
References: <fb95011e666ffd6528d0b57542d7097f.squirrel@grant.boldlygoingnowhere.org>
grant@amadensor.com writes:
> Here is the fun part. When running 8 threads spinning calculating square
> roots (using the stress package), the full scan returned consistently 60%
> faster than the machine with no load.
Possibly the synchronized-seqscans logic kicking in, resulting in this
guy not having to do all his own I/Os. It would be difficult to make
any trustworthy conclusions about performance in such cases from a view
of only one process's results --- you'd need to look at the aggregate
behavior to understand what's happening.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, grant@amadensor.com
Subject: Re: Fun little performance IMPROVEMENT...
In-Reply-To: <17636.1295639447@sss.pgh.pa.us>
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