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

From: Ekaterina Sokolova <e(dot)sokolova(at)postgrespro(dot)ru>
To: pryzby(at)telsasoft(dot)com, lukas(at)fittl(dot)com, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: [PATCH] Add extra statistics to explain for Nested Loop
Date: 2022-02-02 21:59:03
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Hi, hackers.

I apply the new version of patch.

Justin Pryzby <pryzby(at)telsasoft(dot)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 ...

Lukas Fittl <lukas(at)fittl(dot)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:
The Russian Postgres Company

Attachment Content-Type Size
extra_statistics_v6.patch text/x-diff 20.0 KB
overhead_v0.txt text/plain 1.1 KB

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