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>, pgsql-hackers@lists.postgresql.org
Date: 2025-02-22T00:04:31Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> Well, not quite yet, at least. There are two buildfarm failures since
> I committed this. The first is here:

A very significant fraction of the buildfarm is now pink.
If you don't have a fix pretty nearly ready, please revert.

> I imagine what happened here is that the parallel workers didn't
> start, and so nloops was 1 instead of >1, and so we got an integer
> output instead of a fractional one.

Sounds plausible.  I note that this run:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skimmer&dt=2025-02-21%2023%3A00%3A10

got through a couple of iterations of the core tests before failing,
showing that it's not 100% reproducible even on the machines where
it's happening.

			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.