Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id EC01B64FD23 for ; Tue, 22 Jul 2008 11:46:58 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 75521-03-4 for ; Tue, 22 Jul 2008 11:46:07 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 0EE2865016A for ; Tue, 22 Jul 2008 11:46:04 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id m6MEjxJQ028168; Tue, 22 Jul 2008 10:45:59 -0400 (EDT) To: valiouk@yahoo.co.uk cc: pgsql-docs@postgreSQL.org, dx k9 Subject: Re: [ADMIN] shared_buffers and shmmax In-reply-to: <818191.79570.qm@web25804.mail.ukl.yahoo.com> References: <818191.79570.qm@web25804.mail.ukl.yahoo.com> Comments: In-reply-to Valentin Bogdanov message dated "Tue, 22 Jul 2008 14:08:32 -0000" Date: Tue, 22 Jul 2008 10:45:59 -0400 Message-ID: <28167.1216737959@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200807/6 X-Sequence-Number: 4937 [ redirecting to pgsql-docs ] Valentin Bogdanov writes: >> From: dx k9 >> I'm trying to understand what the documentation means >> by bytes per increment, what is the increment supposed to >> be bytes, MB, or Kb. > shared_buffers is in disk block size, typically 8K, at least that's what it is on Linux platforms. shmmax is quite simply in bytes. The table the OP is looking at (table 17.2 in the 8.3 docs) predates the ability to specify shared_buffers in KB or MB instead of number-of-buffers. I agree it's not entirely obvious that what it means is "multiply your setting in KB/MB by 8400/8192". Anybody have an idea how to clarify things? regards, tom lane