From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Smith <greg@2ndquadrant.com>
Cc: Stephen Frost <sfrost@snowman.net>
Cc: Euler Taveira de Oliveira <euler@timbira.com>
Cc: Pgsql Hackers <pgsql-hackers@postgresql.org>
Subject: Re: [PERFORM] pgbench to the MAXINT
Date: Thu, 10 Feb 2011 22:18:38 -0500
Message-ID: <12987.1297394318@sss.pgh.pa.us> (raw)
In-Reply-To: <4D549E92.4010709@2ndquadrant.com>
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<4D549E92.4010709@2ndquadrant.com>
Greg Smith <greg@2ndquadrant.com> writes:
> Poking around a bit more, I just discovered another possible approach is
> to use erand48 instead of rand in pgbench, which is either provided by
> the OS or emulated in src/port/erand48.c That's way more resolution
> than needed here, given that 2^48 pgbench accounts would be a scale of
> 2.8M, which makes for a database of about 42 petabytes.
I think that might be a good idea --- it'd reduce the cross-platform
variability of the results quite a bit, I suspect. random() is not
to be trusted everywhere, but I think erand48 is pretty much the same
wherever it exists at all (and src/port/ provides it elsewhere).
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, greg@2ndquadrant.com, sfrost@snowman.net, euler@timbira.com, pgsql-hackers@postgresql.org
Subject: Re: [PERFORM] pgbench to the MAXINT
In-Reply-To: <12987.1297394318@sss.pgh.pa.us>
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