Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 955611337BA6 for ; Fri, 11 Feb 2011 09:35:58 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 59863-03 for ; Fri, 11 Feb 2011 13:35:51 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from tamriel.snowman.net (tamriel.snowman.net [72.66.115.51]) by mail.postgresql.org (Postfix) with ESMTP id 58D0F133616B for ; Fri, 11 Feb 2011 09:35:51 -0400 (AST) Received: by tamriel.snowman.net (Postfix, from userid 1000) id 2BC1F2219D; Fri, 11 Feb 2011 08:35:51 -0500 (EST) Date: Fri, 11 Feb 2011 08:35:51 -0500 From: Stephen Frost To: Tom Lane Cc: Greg Smith , Euler Taveira de Oliveira , Pgsql Hackers Subject: Re: [PERFORM] pgbench to the MAXINT Message-ID: <20110211133551.GE4116@tamriel.snowman.net> References: <4D27C4E5.5000609@2ndquadrant.com> <4D2A965A.3000603@timbira.com> <4D2AC273.3010709@2ndquadrant.com> <4D2CCCD9.802@timbira.com> <4D35DF33.6060901@2ndquadrant.com> <4D5017DE.90404@2ndquadrant.com> <4D525281.1000201@2ndquadrant.com> <20110209194008.GX4116@tamriel.snowman.net> <4D549E92.4010709@2ndquadrant.com> <12987.1297394318@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="t3tFFy74pA5/PEcJ" Content-Disposition: inline In-Reply-To: <12987.1297394318@sss.pgh.pa.us> X-Editor: Vim http://www.vim.org/ X-Info: http://www.snowman.net X-Operating-System: Linux/2.6.32-5-amd64 (x86_64) X-Uptime: 08:35:17 up 8 days, 22:05, 17 users, load average: 0.00, 0.04, 0.00 User-Agent: Mutt/1.5.20 (2009-06-14) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-5 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201102/940 X-Sequence-Number: 181729 --t3tFFy74pA5/PEcJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Greg, * Tom Lane (tgl@sss.pgh.pa.us) wrote: > Greg Smith writes: > > Poking around a bit more, I just discovered another possible approach i= s=20 > > to use erand48 instead of rand in pgbench, which is either provided by= =20 > > the OS or emulated in src/port/erand48.c That's way more resolution=20 > > than needed here, given that 2^48 pgbench accounts would be a scale of= =20 > > 2.8M, which makes for a database of about 42 petabytes. >=20 > 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). Works for me. Greg, will you be able to work on this change? If not, I might be able to. Thanks, Stephen --t3tFFy74pA5/PEcJ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAk1VOzcACgkQrzgMPqB3kigCfQCfdbIqiUyW0LocVZQt1LnqMNLa o2UAoJQ8bP8wIyP1/ihL2y4s+MEsZF7l =bsRj -----END PGP SIGNATURE----- --t3tFFy74pA5/PEcJ--