X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id ACF049DCBC0 for ; Sat, 3 Dec 2005 12:20:35 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 63311-08 for ; Sat, 3 Dec 2005 12:20:33 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from floppy.pyrenet.fr (news.pyrenet.fr [194.116.145.2]) by postgresql.org (Postfix) with ESMTP id C9DC49DCA94 for ; Sat, 3 Dec 2005 12:20:32 -0400 (AST) Received: by floppy.pyrenet.fr (Postfix, from userid 106) id A0CA03093A; Sat, 3 Dec 2005 17:20:31 +0100 (MET) From: Michael Riess X-Newsgroups: pgsql.performance Subject: Re: 15,000 tables - next step Date: Sat, 03 Dec 2005 17:20:21 +0100 Organization: Hub.Org Networking Services Lines: 38 Message-ID: References: <4391BF0F.9000208@Yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@news.hub.org User-Agent: Thunderbird 1.5 (Windows/20051025) In-Reply-To: <4391BF0F.9000208@Yahoo.com> To: pgsql-performance@postgresql.org X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0 required=5 tests=[none] X-Spam-Score: 0 X-Spam-Level: X-Archive-Number: 200512/98 X-Sequence-Number: 15919 Jan Wieck schrieb: > On 12/2/2005 6:01 PM, Michael Riess wrote: > >> Hi, >> >> thanks for your comments so far - I appreciate it. I'd like to narrow >> down my problem a bit: >> >> As I said in the other thread, I estimate that only 20% of the 15,000 >> tables are accessed regularly. So I don't think that vacuuming or the >> number of file handles is a problem. Have a look at this: > > What makes you think that? Have you at least tried to adjust your shared > buffers, freespace map settings and background writer options to values > that match your DB? How does increasing the kernel file desctriptor > limit (try the current limit times 5 or 10) affect your performance? > > Of course I tried to tune these settings. You should take into account that the majority of the tables are rarely ever modified, therefore I don't think that I need a gigantic freespace map. And the background writer never complained. Shared memory ... I currently use 1500 buffers for 50 connections, and performance really suffered when I used 3000 buffers. The problem is that it is a 1GB machine, and Apache + Tomcat need about 400MB. But thanks for your suggestions! I guess that I'll have to find a way to reduce the number of tables. Unfortunately my application needs them, so I'll have to find a way to delete rarely used tables and create them on the fly when they're accessed again. But this will really make my application much more complex and error-prone, and I had hoped that the database system could take care of that. I still think that a database system's performance should not suffer from the mere presence of unused tables. Mike