From: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>
To: Jignesh K. Shah <J.K.Shah@Sun.COM>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Heikki Linnakangas <heikki@enterprisedb.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: PostgreSQL publishes first real benchmark
Date: Thu, 12 Jul 2007 11:08:38 +0200
Message-ID: <4695EF96.3060009@kaltenbrunner.cc> (raw)
In-Reply-To: <469522A5.1070409@sun.com>
References: <46925AD9.9020208@sun.com>
<4694FE64.8070407@enterprisedb.com>
<4695063D.9040108@sun.com>
<27436.1184173639@sss.pgh.pa.us>
<469522A5.1070409@sun.com>
Jignesh K. Shah wrote:
> Can you list others that seemed out of place?
well to me the ones that look most questionable are:
work_mem=100MB - so this benchmark is really low concurrency(which does
not fit with max_connections=1000) and with trivial queries ?
enable_seqscan = off - why ?
effective_cache_size = 40GB - on a box with 16GB this seems wrong
especially since there are some indications out there that suggest that
while overestimating effective_cache_size was not a problem in versions
<8.2 it might not be so in 8.2 and up
wal_buffers = 2300 - there have been some numbers reported that going
over the default of 8 helps but it is generally considered that going
beyond 500 or maybe 1000 does not help at all ...
and one more is that you claim you used "-fast -O4 -xtarget=ultraT1"
which is something we explicitly advise against in our own
FAQ(http://www.postgresql.org/docs/faqs.FAQ_Solaris.html):
"Do not use any flags that modify behavior of floating point operations
and errno processing (e.g.,-fast). These flags could raise some
nonstandard PostgreSQL behavior for example in the date/time computing."
Stefan
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Cc: stefan@kaltenbrunner.cc, J.K.Shah@Sun.COM, tgl@sss.pgh.pa.us, heikki@enterprisedb.com
Subject: Re: PostgreSQL publishes first real benchmark
In-Reply-To: <4695EF96.3060009@kaltenbrunner.cc>
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