| From: | Andrei Lepikhov <lepihov(at)gmail(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com>, Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com> |
| Cc: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)lists(dot)postgresql(dot)org, Guillaume Lelarge <guillaume(at)lelarge(dot)info>, Matheus Alcantara <matheusssilv97(at)gmail(dot)com>, Alena Rybakina <a(dot)rybakina(at)postgrespro(dot)ru> |
| Subject: | Re: explain analyze rows=%.0f |
| Date: | 2025-04-01 05:20:37 |
| Message-ID: | ae90d15d-54e5-4caa-ba72-5bbed9b2c908@gmail.com |
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| Lists: | pgsql-hackers |
On 3/31/25 19:35, Robert Haas wrote:
> But why isn't it just as valuable to have two decimal places for the
> estimate? I theorize that the cases that are really a problem here are
> those where the row count estimate is between 0 and 1 per row, and
> rounding to an integer loses all precision.
Issues I've ever seen were about zero rows number - we lose
understanding of what the job the executor has done in the node - loops
= 10000000 doesn't tell us any helpful information in that case.
Maybe in the next version, we replace the two fractional numbers rule
with two valuable numbers. At least, it removes boring xxx.00 numbers
from EXPLAIN.
--
regards, Andrei Lepikhov
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