Horton

Re: explain analyze rows=%.0f

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>, Andrei Lepikhov <lepihov@gmail.com>, Matheus Alcantara <matheusssilv97@gmail.com>, Guillaume Lelarge <guillaume@lelarge.info>, Daniel Gustafsson <daniel@yesql.se>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, "Gregory Stark (as CFM)" <stark.cfm@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, Peter Geoghegan <pg@bowt.ie>, vignesh C <vignesh21@gmail.com>, "David G. Johnston" <david.g.johnston@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2025-02-12T18:40:15Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> I agree that showing 2 digits after the decimal point in all cases is
> not ideal, but I suggest that we take a practical approach. Figuring
> out dynamically what number of decimal digits to display in each case
> sounds complicated and we may spend a bunch of time arguing about the
> details of that and get nothing committed. If we just show 2 digits
> after the decimal point, it will not be perfect, but it will be 10^2
> times better than what we have now.

I was idly speculating yesterday about letting the Ryu code print
the division result, so that we get a variable number of digits.
Realistically, that'd probably result in many cases in more digits
than anybody wants, so it's not a serious proposal.  I'm cool with
the fixed-two-digits approach to start with.

			regards, tom lane

Commits

  1. EXPLAIN: Always use two fractional digits for row counts.

  2. Adjust EXPLAIN test case to filter out "Actual Rows" values.

  3. Allow EXPLAIN to indicate fractional rows.

  4. Fix pgbench performance issue induced by commit af35fe501.