Horton

Re: explain analyze rows=%.0f

Greg Stark <stark@mit.edu>

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From: Greg Stark <stark@mit.edu>
To: vignesh C <vignesh21@gmail.com>
Cc: Ibrar Ahmed <ibrar.ahmad@gmail.com>, "David G. Johnston" <david.g.johnston@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Simon Riggs <simon@2ndquadrant.com>, Ron Mayer <rm_pg@cheapcomplexdevices.com>, Euler Taveira de Oliveira <euler@timbira.com>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2022-07-07T17:53:16Z
Lists: pgsql-hackers 
> -               ->  Parallel Seq Scan on tenk1 (actual rows=1960 loops=50)
> +               ->  Parallel Seq Scan on tenk1 (actual rows=1960.00

At the not inconsiderable risk of bike-shedding....

I'm wondering if printing something like 0.00 will be somewhat
deceptive when the real value is non-zero but less than 1 row per 200
loops. I wonder if the number of decimal places should be calculated
to produce a minimum of one non-zero digit for non-zero values.

-- 
greg

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.