AW: Strange query execution time - Mailing list pgsql-hackers

From Zeugswetter Andreas SB
Subject AW: Strange query execution time
Date
Msg-id 11C1E6749A55D411A9670001FA687963368361@sdexcsrv1.f000.d0188.sd.spardat.at
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Responses Re: AW: Strange query execution time
List pgsql-hackers
> Can  someone explain why the following query takes  1 second when using 
> LIKE and takes 30 seconds when replacing LIKE by = in the WHERE ? 

Because there is no optimization built in, that notices, that your
string does not contain a wildcard and would translate the restriction 
correspondingly. It is currently executed more or less like below:(I3.nameInfluence >= 'inf_vitesse' and
I3.nameInfluence< 'inf_vitessf'     and I3.nameInfluence LIKE  'inf_vitesse')
 
I already wanted to try to add this optimization myself, but lacked the time so far.
Anybody want to volunteer ?

TODO: add LIKE optimization to use = if constant does not contain any wildcards

Andreas


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