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From: Tom Lane <[email protected]>
To: Robert Haas <[email protected]>
Cc: Andrei Lepikhov <[email protected]>
Cc: Ilia Evdokimov <[email protected]>
Cc: Matheus Alcantara <[email protected]>
Cc: Guillaume Lelarge <[email protected]>
Cc: Daniel Gustafsson <[email protected]>
Cc: Ibrar Ahmed <[email protected]>
Cc: Gregory Stark (as CFM) <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: Justin Pryzby <[email protected]>
Cc: Peter Geoghegan <[email protected]>
Cc: vignesh C <[email protected]>
Cc: David G. Johnston <[email protected]>
Cc: [email protected]
Subject: Re: explain analyze rows=%.0f
Date: Tue, 11 Feb 2025 15:46:43 -0500
Message-ID: <[email protected]> (raw)
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Robert Haas <[email protected]> writes:
> On Tue, Feb 11, 2025 at 12:14 PM Andrei Lepikhov <[email protected]> wrote:
>> I support the idea in general, but I believe it should be expanded to
>> cover all cases of parameterised plan nodes. Each rescan iteration may
>> produce a different number of tuples, and rounding can obscure important
>> data.

> I agree strongly with all of this. I believe we should just implement
> what was agreed here:
> https://www.postgresql.org/message-id/21013.1243618236%40sss.pgh.pa.us
> Let's just display 2 fractional digits when nloops>1, else 0, and call it good.

Note that that formulation has nothing especially to do with
parameterized plan nodes.  Any nestloop inner side would end up
getting shown with fractional rowcounts.  Maybe that's fine.

I suggest that when thinking about what to change here,
you start by considering how you'd adjust the docs at
https://www.postgresql.org/docs/devel/using-explain.html
to explain the new behavior.  If you can't explain it
clearly for users, then maybe it's not such a great idea.

			regards, tom lane






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