Re: Fun little performance IMPROVEMENT...

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: grant(at)amadensor(dot)com
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Fun little performance IMPROVEMENT...
Date: 2011-01-21 19:50:47
Message-ID: 17636.1295639447@sss.pgh.pa.us
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grant(at)amadensor(dot)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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