Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 182A664FDBB for ; Wed, 17 Dec 2008 09:53:58 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 78294-09 for ; Wed, 17 Dec 2008 09:53:52 -0400 (AST) 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 mail.postgresql.org (Postfix) with ESMTP id 818FA64FD73 for ; Wed, 17 Dec 2008 09:53:51 -0400 (AST) 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 mBHDriWe027842; Wed, 17 Dec 2008 08:53:44 -0500 (EST) To: Bruce Momjian cc: Alvaro Herrera , valiouk@yahoo.co.uk, pgsql-docs@postgresql.org, dx k9 Subject: Re: [ADMIN] shared_buffers and shmmax In-reply-to: <200812171341.mBHDfeK11281@momjian.us> References: <200812171341.mBHDfeK11281@momjian.us> Comments: In-reply-to Bruce Momjian message dated "Wed, 17 Dec 2008 08:41:40 -0500" Date: Wed, 17 Dec 2008 08:53:44 -0500 Message-ID: <27841.1229522024@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: 200812/22 X-Sequence-Number: 5029 Bruce Momjian writes: > Tom Lane wrote: >> * If we do it like this then the left-hand column is really redundant, >> not to say wrong because the right-hand formulas depend on more than >> the single variable mentioned. How about something like >> >> Table 17-2 PostgreSQL shared memory usage >> >> Purpose Approximate number of bytes required (as of 8.3) >> >> Per-connection state (1800 + 270 * max_locks_per_transaction) * max_connections >> Autovacuum worker state (1800 + 270 * max_locks_per_transaction) * autovacuum_max_workers >> Prepared transaction state ... >> Shared disk buffers ... >> WAL buffers ... >> Fixed space requirements 770kB > OK, I updated it again: > http://momjian.us/tmp/pgsql/kernel-resources.html > I did change your left column wording because it could be interpreted as > something that changes during server execution, e.g. connections. [ shrug... ] I don't find what you did to be an improvement over what I suggested, but I don't have time to argue about it. regards, tom lane