Re: explain analyze rows=%.0f - Mailing list pgsql-hackers

From Tom Lane
Subject Re: explain analyze rows=%.0f
Date
Msg-id 11926.1243953507@sss.pgh.pa.us
Whole thread Raw
In response to Re: explain analyze rows=%.0f  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: explain analyze rows=%.0f  (Robert Haas <robertmhaas@gmail.com>)
Re: explain analyze rows=%.0f  (Ibrar Ahmed <ibrar.ahmad@gmail.com>)
List pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> On Jun 2, 2009, at 9:41 AM, Simon Riggs <simon@2ndQuadrant.com> wrote:
>> You're right that the number of significant digits already exceeds the
>> true accuracy of the computation. I think what Robert wants to see is
>> the exact value used in the calc, so the estimates can be checked more
>> thoroughly than is currently possible.

> Bingo.

Uh, the planner's estimate *is* an integer.  What was under discussion
(I thought) was showing some fractional digits in the case where EXPLAIN
ANALYZE is outputting a measured row count that is an average over
multiple loops, and therefore isn't necessarily an integer.  In that
case the measured value can be considered arbitrarily precise --- though
I think in practice one or two fractional digits would be plenty.
        regards, tom lane


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