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List:       postgresql-sql
Subject:    Re: [SQL] join on three tables is slow
From:       Gerry Reno <greno () verizon ! net>
Date:       2007-12-12 14:29:49
Message-ID: 475FF05D.9040009 () verizon ! net
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Tom Lane wrote:
> Gerry Reno <greno@verizon.net> writes:
>   
>> Pavel Stehule wrote:
>>     
>>> there is diference in agg position. Send, please, query and explain
>>> analyze output.
>>>       
>
> [ explain analyze output ]
>
> The rowcount estimates seem pretty far off, even for simple cases that
> I'd expect it to get right, eg
>
>   
>>          ->  Seq Scan on res_partner_address a  (cost=0.00..88.40 
>> rows=16 width=552) (actual time=0.851..16.131 rows=559 loops=1)
>>                Filter: ((("type")::text = 'default'::text) OR ("type" IS 
>> NULL))
>>     
>
> Are the ANALYZE stats up to date for these tables?
>
> What PG version is this, anyway?
>
> 			regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
>
>   
-bash-3.2$ yum list postgresql
Loading "installonlyn" plugin
Installed Packages
postgresql.i386                          8.2.4-1.fc7            
installed      

You were right on the money Tom.  I vacuumed the database and now the 
query with the boolean executes in only 50% more time than without.  
About 15 secs instead of 10 secs.  Big improvement.  I hadn't seen a 
vacuum produce this much of an improvement in performance before.

Thanks,
Gerry


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