Re: Query Tuning

Tom Lane wrote:

>Pallav Kalva <pkalva(at)deg(dot)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.