Subject: Re: Query planner issue
From: Mark Lewis <mark.lewis@mir3.com>
To: Emmanuel Lacour <elacour@easter-eggs.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <20060130225711.GE1320@easter-eggs.com>
References: <20060130225711.GE1320@easter-eggs.com>
Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Organization: MIR3, Inc.
Date: Mon, 30 Jan 2006 15:26:23 -0800
Message-Id: <1138663583.28241.96.camel@archimedes>
Mime-Version: 1.0

You have lots of dead rows.  Do a vacuum full to get it under control,
then run VACUUM more frequently and/or increase your FSM settings to
keep dead rows in check.  In 7.2 vacuum is pretty intrusive; it will be
much better behaved once you can upgrade to a more recent version.

You really, really want to upgrade as soon as possible, and refer to the
on-line docs about what to do with your FSM settings.

-- Mark Lewis


On Mon, 2006-01-30 at 23:57 +0100, Emmanuel Lacour wrote:
> Hi everybody,
> 
> I have the following problem, on a test server, if I do a fresh import
> of production data then run 
> 'explain analyze select count(*) from mandats;'
> 
> I get this result:
> 
> Aggregate  (cost=6487.32..6487.32 rows=1 width=0) (actual time=607.61..607.61 rows=1 loops=1)
>   ->  Seq Scan on mandats  (cost=0.00..6373.26 rows=45626 width=0) (actual time=0.14..496.20 rows=45626 loops=1)
>   Total runtime: 607.95 msec
> 
> 
> On the production server, if I do the same (without other use of the server), I get:
> 
> Aggregate  (cost=227554.33..227554.33 rows=1 width=0) (actual time=230705.79..230705.79 rows=1 loops=1)
>   ->  Seq Scan on mandats  (cost=0.00..227440.26 rows=45626 width=0) (actual time=0.03..230616.64 rows=45760 loops=1)
>   Total runtime: 230706.08 msec
> 
> 
> 
> Is there anyone having an idea on how yo solve this poor performances? I
> think it is caused by many delete/insert on this table every day, but
> how to solve it, I need to run this qury each hour :(. I run
> vacuum each night, postgresql is unfortunatly 7.2.1 :( (no upgrade
> before 2 or 3 months).
>