Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 662596500E7 for ; Wed, 17 Dec 2008 10:11:31 -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 82466-02 for ; Wed, 17 Dec 2008 10:11:24 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from momjian.us (momjian.us [70.90.9.53]) by mail.postgresql.org (Postfix) with ESMTP id D0FA664FE31 for ; Wed, 17 Dec 2008 10:11:24 -0400 (AST) Received: (from bruce@localhost) by momjian.us (8.11.6/8.11.6) id mBHEBKX26736; Wed, 17 Dec 2008 09:11:20 -0500 (EST) From: Bruce Momjian Message-Id: <200812171411.mBHEBKX26736@momjian.us> Subject: Re: [ADMIN] shared_buffers and shmmax In-Reply-To: <27841.1229522024@sss.pgh.pa.us> To: Tom Lane Date: Wed, 17 Dec 2008 09:11:20 -0500 (EST) CC: Alvaro Herrera , valiouk@yahoo.co.uk, pgsql-docs@postgresql.org, dx k9 X-Mailer: ELM [version 2.4ME+ PL124 (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="US-ASCII" 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: 200812/23 X-Sequence-Number: 5030 Tom Lane wrote: > 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. I decided I didn't like what I did either; updated version with new headings and shorter descriptions: http://momjian.us/tmp/pgsql/kernel-resources.html -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. +