Message-ID: <4166CE72.2050900@deg.cc>
Date: Fri, 08 Oct 2004 13:29:22 -0400
From: Pallav Kalva <pkalva@deg.cc>
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To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query Tuning
References: <4166A8E8.4060102@deg.cc> <13657.1097253776@sss.pgh.pa.us>
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Tom Lane wrote:

>Pallav Kalva <pkalva@deg.cc> writes:
>  
>
>>      I have a problem with the below query, when i do explain on the 
>>below query on my live database it doesnt use any index specified on the 
>>tables and does seq scan on the table which is 400k records. But if i 
>>copy the same table onto a different database on a different machine it 
>>uses all the indexes specified and query runs much quicker.
>>    
>>
>
>It looks to me like you've never vacuumed/analyzed the copy, and so you
>get a different plan there.  The fact that that plan is better than the
>one made with statistics is unhappy making :-( ... but when you only
>show us EXPLAIN output rather than EXPLAIN ANALYZE, it's impossible to
>speculate about why.  Also, what PG version is this?
>
>			regards, tom lane
>
>  
>
Thanks! for the quick reply. I cant run the EXPLAIN ANALYZE on the live 
database because, it takes lot of time and hols up lot of other queries 
on the table. The postgres version I  am using is 7.4 . when you say " i 
never vacuum/analyxed the copy" you mean the Live database ? or the copy 
of the live database ? . I run vacuum database daily on my live database 
as a part of daily maintanence.