Re: EXPLAIN: showing ReadStream / prefetch stats

Tomas Vondra <tomas@vondra.me>

From: Tomas Vondra <tomas@vondra.me>

To: Andres Freund <andres@anarazel.de>

Cc: Melanie Plageman <melanieplageman@gmail.com>, Lukas Fittl <lukas@fittl.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2026-05-04T13:51:20Z

Lists: pgsql-hackers

Attachments

0001-Improve-docs-for-EXPLAIN-IO.patch (text/x-patch)

Hi,

While looking for something in the EXPLAIN docs, I realized the docs
added by 681daed93169 are considerably less detailed that for the other
EXPLAIN options. It only said "information on I/O" provided by the scan
node, while the other options go into much more details.

The attached patch improves that a little bit - it lists the counters
added to explain. I'll consider going into a little bit more detail,
e.g. regarding what "capacity" or "waits" means.

I'll add this as an open item for PG19, so that I don't forget about it.

regards

-- 
Tomas Vondra