Date: Tue, 30 Aug 2005 08:13:22 -0500
From: Frank Wiles <frank@wiles.org>
To: "Akshay Mathur" <akshay.mathur@airtightnetworks.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: Observation about db response time
Message-Id: <20050830081322.20a13d4f.frank@wiles.org>
In-Reply-To: <003401c5ad63$8420d940$9701a8c0@pune.wibhu.com>
References: <003401c5ad63$8420d940$9701a8c0@pune.wibhu.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

On Tue, 30 Aug 2005 18:35:30 +0530
"Akshay Mathur" <akshay.mathur@airtightnetworks.net> wrote:

> Hello Friends,
>  
> We were having a database in pgsql7.4.2 The database was responding
> very slowly even after full vacuum analyze (select count(*) from
> some_table_having_18000_records was taking 18 Sec).
>  
> We took a backup of that db and restored it back. Now the same db on
> same PC is responding fast (same query is taking 18 ms).
>  
> But we can't do the same as a solution of slow response. Do anybody
> has faced similar problem? Is this due to any internal problem of
> pgsql? Is there any clue to fasten the database?

  This could be because you don't have max_fsm_pages and
  max_fsm_relations setup correctly or are not doing full vacuums 
  often enough. 

  If your database deletes a ton of data as a matter of course then
  sometimes a full vacuum will not clear up as much space as it could.

  Try increasing those configuration values and doing vacuums more
  often. 

  If you should also explore upgrading to the latest 8.0 as you will
  no doubt see noticeable speed improvements. 

 ---------------------------------
   Frank Wiles <frank@wiles.org>
   http://www.wiles.org
 ---------------------------------