On 10/11/2025 18:11, Andres Freund wrote:
Hi,
On 2025-11-10 13:29:08 +0200, Heikki Linnakangas wrote:
At the "make mxidoff 64 bits" thread [1], we're discussing moving
SLRU_PAGES_PER_SEGMENT to pg_config_manual.h, to make it accessible from
pg_upgrade code. It's currently defined in slru.h, which cannot be included
in frontend code. There are many ways we could fix that, but moving
SLRU_PAGES_PER_SEGMENT to pg_config_manual.h seems best to me. Patch
attached.
I'm not convinced that pg_config_manual.h is a good place - that suggests it
makes sense to change the value for some installations, which I don't see any
reason for. Wouldn't an slrudefs.h or such be more appropriate?
The comment in pg_config_manual.h says about settings defined there:
In all cases, changing them is only useful in very rare situations
or for developers.
That seems fitting for SLRU_PAGES_PER_SEGMENT. I don't feel strongly
either way though, I'm happy to revert and move to slrudefs.h if that's
the consensus.
I think the control file compatibility check is nice to have in any case
and we should keep that.
- Heikki
