Re: Help optimize view - Mailing list pgsql-performance

From Tom Lane
Subject Re: Help optimize view
Date
Msg-id 14336.1186782218@sss.pgh.pa.us
Whole thread Raw
In response to Re: Help optimize view  ("Relyea, Mike" <Mike.Relyea@xerox.com>)
Responses Re: Help optimize view
List pgsql-performance
"Relyea, Mike" <Mike.Relyea@xerox.com> writes:
> SELECT "PrintSamples"."MachineID", "PrintSamples"."PrintCopyID",
> "tblColors"."ColorID", avg("ParameterValues"."ParameterValue") AS
> "Mottle_NMF"
>    FROM "AnalysisModules"
>    JOIN ("tblColors"
>    JOIN ("tblTPNamesAndColors"
>    JOIN "PrintSamples" ON "tblTPNamesAndColors"."TestPatternName"::text
> =3D "PrintSamples"."TestPatternName"::text
>    JOIN ("DigitalImages"
>    JOIN "PrintSampleAnalyses" ON "DigitalImages"."ImageID" =3D
> "PrintSampleAnalyses"."ImageID"
>    JOIN ("ParameterNames"
>    JOIN ("Measurements"
>    JOIN "ParameterValues" ON "Measurements"."MeasurementID" =3D
> "ParameterValues"."MeasurementID") ON "ParameterNames"."ParameterID" =3D
> "ParameterValues"."ParameterID") ON "PrintSampleAnalyses"."psaID" =3D
> "Measurements"."psaID") ON "PrintSamples"."PrintSampleID" =3D
> "DigitalImages"."PrintSampleID") ON "tblColors"."ColorID" =3D
> "tblTPNamesAndColors"."ColorID") ON "AnalysisModules"."MetricID" =3D
> "Measurements"."MetricID"

Try increasing join_collapse_limit --- you have just enough tables here
that the planner isn't going to consider all possible join orders.
And it sorta looks like it's picking a bad one.

            regards, tom lane

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