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From: Kevin Grittner <Kevin.Grittner@wicourts.gov>
To: pgsql-performance@postgresql.org
To: Mike Relyea <Mike.Relyea@xerox.com>
Subject: Re: Help optimize view
Date: Sat, 18 Aug 2007 20:01:50 -0500
Message-ID: <46C7502D.EE98.0025.0@wicourts.gov> (raw)
In-Reply-To: <1806D1F73FCB7F439F2C842EE0627B18065BEC18@usa0300ms01.na.xerox.net>
References: <1806D1F73FCB7F439F2C842EE0627B18065BEC18@usa0300ms01.na.xerox.net>

>>> On Fri, Aug 10, 2007 at 11:57 AM, in message
<1806D1F73FCB7F439F2C842EE0627B18065BEC18@usa0300ms01.na.xerox.net>, "Relyea,
Mike" <Mike.Relyea@xerox.com> wrote: 
> I'm have the following view as part of a larger, aggregate query that is
> running slower than I'd like.
> . . .
> HAVING "PrintSamples"."MachineID" = 4741 OR "PrintSamples"."MachineID" =
> 4745 AND "AnalysisModules"."AnalysisModuleName" = 'NMF' AND
> "ParameterNames"."ParameterName" = 'NMF' AND "tblColors"."ColorID" <> 3
> AND "PrintSamples"."TestPatternName" LIKE 'IQAF-TP8%';
 
First off, let's make sure we're optimizing the query you really want to run.
AND binds tighter than OR, so as you have it written, it is the same as:
 
  HAVING "PrintSamples"."MachineID" = 4741
      OR (   "PrintSamples"."MachineID" = 4745
         AND "AnalysisModules"."AnalysisModuleName" = 'NMF'
         AND "ParameterNames"."ParameterName" = 'NMF'
         AND "tblColors"."ColorID" <> 3
         AND "PrintSamples"."TestPatternName" LIKE 'IQAF-TP8%';
         )
 
I fear you may really want it evaluate to:
 
  HAVING ("PrintSamples"."MachineID" = 4741 OR "PrintSamples"."MachineID" = 4745)
     AND "AnalysisModules"."AnalysisModuleName" = 'NMF'
     AND "ParameterNames"."ParameterName" = 'NMF'
     AND "tblColors"."ColorID" <> 3
     AND "PrintSamples"."TestPatternName" LIKE 'IQAF-TP8%';
 
-Kevin
 





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  Subject: Re: Help optimize view
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