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DB2 Query Optimisation

 
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prasadplease

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Joined: 02 Sep 2006
Posts: 31
Location: Mumbai

PostPosted: Thu Jul 09, 2009 4:48 pm    Post subject: DB2 Query Optimisation
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Hi below is my query...it is taking a lot of time...can anyone suggest ways to optimise this query

select a,b,c,d
from view1
where digits(a*10 + b) in (:t1, :t2, :t3)
order by a,b,c,d

Thanks.
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Bharath Bhat

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Joined: 20 Mar 2008
Posts: 283
Location: chennai

PostPosted: Thu Jul 09, 2009 4:53 pm    Post subject:
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Try to avoid calculations in the query. It may yield better results if you break it down to two queries.
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rajnikantvanpratiwar

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Joined: 01 Jul 2009
Posts: 5
Location: Pune

PostPosted: Thu Jul 09, 2009 5:00 pm    Post subject:
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check once whether you are using index part in you query or not and if not then try using it so tht query retrieves data in fast way....
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dbzTHEdinosauer

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Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne

PostPosted: Thu Jul 09, 2009 5:19 pm    Post subject:
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why not make t1, t2 and t3 non-char datatype?
the digits scalar function should be removed.
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ashimer

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Joined: 13 Feb 2004
Posts: 551
Location: Bangalore

PostPosted: Thu Jul 09, 2009 7:34 pm    Post subject:
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Try not to use calculations in where clause ...

Code:


select a,b,c,d from (
select a,b,c,d, digits(a*10 + b) as s
from view1 ) as a
where s in (:t1, :t2, :t3)
order by a,b,c,d

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