Re: [PATCH] Add extra statistics to explain for Nested Loop

Ekaterina Sokolova <e.sokolova@postgrespro.ru>

From: Ekaterina Sokolova <e.sokolova@postgrespro.ru>
To: pryzby@telsasoft.com, lukas@fittl.com, pgsql-hackers@lists.postgresql.org
Date: 2022-02-02T21:59:03Z
Lists: pgsql-hackers

Attachments

Hi, hackers.

I apply the new version of patch.

Justin Pryzby <pryzby@telsasoft.com> wrote:
> I'm curious to hear what you and others think of the refactoring.
Thank you so much. With your changes, the patch has become more 
understandable and readable.

> It'd be nice if there's a good way to add a test case for verbose 
> output
> involving parallel workers, but the output is unstable ...
Done!

Lukas Fittl <lukas@fittl.com> wrote:
> I've briefly thought whether this needs documentation (currently the 
> patch includes none),
> but there does not appear to be a good place to add documentation about 
> this from a
> quick glance, so it seems acceptable to leave this out given the lack 
> of more detailed
> EXPLAIN documentation in general.
You're right! I added feature description to the patch header.

> Whilst no specific bad cases were provided, I wonder if even a simple 
> pgbench with
> auto_explain (and log_analyze=1) would be a way to test this?
I wanted to measure overheads, but could't choose correct way. Thanks 
for idea with auto_explain.
I loaded it and made 10 requests of pgbench (number of clients: 1, of 
threads: 1).
I'm not sure I chose the right way to measure overhead, so any 
suggestions are welcome.
Current results are in file overhead_v0.txt.

Please feel free to share your suggestions and comments. Regards,

-- 
Ekaterina Sokolova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. Fix wrong units in two ExplainPropertyFloat calls.