Query planner issue

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).

--
Emmanuel Lacour ------------------------------------ Easter-eggs
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