Re: Erroneous cost estimation for nested loop join - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Erroneous cost estimation for nested loop join
Date
Msg-id 22565.1447079844@sss.pgh.pa.us
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In response to Erroneous cost estimation for nested loop join  (kawamichi@tkl.iis.u-tokyo.ac.jp)
Responses Re: Erroneous cost estimation for nested loop join  (KAWAMICHI Ryoji <kawamichi@tkl.iis.u-tokyo.ac.jp>)
Re: Erroneous cost estimation for nested loop join  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-hackers
kawamichi@tkl.iis.u-tokyo.ac.jp writes:
>       - cost parameter calibration: random_page_cost = 92.89

TBH, you lost me there already.  I know of no hardware on which that would
be a sane depiction of reality, so I think you've probably overfitted the
model to some particular case it was already inaccurate on.  Any results
you're getting using this setting will likely fall into the category of
"garbage in, garbage out".

What led you to choose that number?
        regards, tom lane



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