Re: Move SLRU_PAGES_PER_SEGMENT to pg_config_manual.h

Heikki Linnakangas <hlinnaka@iki.fi>

From: Heikki Linnakangas <hlinnaka@iki.fi>
To: Daniel Gustafsson <daniel@yesql.se>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Maxim Orlov <orlovmg@gmail.com>, Daniil Davydov <3danissimo@gmail.com>
Date: 2025-11-10T12:18:46Z
Lists: pgsql-hackers
On 10/11/2025 13:41, Daniel Gustafsson wrote:
> +	uint32		slru_pages_per_segment; /* size of each SLRU segment */
> 
> Should this be expanded ever so slightly?  A new reader of the code might
> wonder about the relationship between "pages_per" and "size".

Hmm, there's not much space for further explanations on that line. We 
could add a longer multi-line comment but I'd rather keep it short and 
consistent with the other similar fields around it. I hope that readers 
who want more information will find the SLRU_PAGES_PER_SEGMENT 
definition and the comments there.

I did consider renaming the field to 'slru_seg_size', to rhyme with 
'relseg_size' and 'xlog_seg_size'. But then it wouldn't match the name 
of SLRU_PAGES_PER_SEGMENT anymore. We could rename 
SLRU_PAGES_PER_SEGMENT too, but I'm not sure it's worth the code churn, 
and IMO "pages per segment" is better than "segment size" anyway because 
it tells you what the unit is.

> No objections (apart from the catversion =)) from reading the patch.

Thanks for the review!

- Heikki




Commits

  1. Add warning to pg_controldata on PG_CONTROL_VERSION mismatch

  2. Add pg_resetwal and pg_controldata support for new control file field

  3. Bump PG_CONTROL_VERSION for commit 3e0ae46d90

  4. Move SLRU_PAGES_PER_SEGMENT to pg_config_manual.h