Re: Planner really hates nested loops - Mailing list pgsql-performance

From Tom Lane
Subject Re: Planner really hates nested loops
Date
Msg-id 16694.1107447931@sss.pgh.pa.us
Whole thread Raw
In response to Planner really hates nested loops  (David Brown <time@bigpond.net.au>)
Responses Re: Planner really hates nested loops
List pgsql-performance
David Brown <time@bigpond.net.au> writes:
> I'm hoping someone can shed some light on these results.

Not without a lot more detail on how you *got* the results.  What
exactly did you do to force the various plan choices?  (I see some
ridiculous choices of indexscans, for instance, suggesting improper use
of enable_seqscan in some cases.)  And what's the "cache rows" and "disk
rows" stuff, and how do you know that what you were measuring is
actually what you think it is?  I have zero confidence in
Windows-atop-ATA as a platform for measuring disk-related behaviors,
because I don't think you can control or even know what caching is
going on.

            regards, tom lane

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