Re: Add pg_stat_kind_info system view

On Thu, Jul 30, 2026 at 08:18:21AM +0900, Michael Paquier wrote:
> In terms of this thread, more thought is a synonym of making sure that
> your proposal [2] is good enough for the purpose to be able to monitor
> the pgstats activity. I'll try to look double-check this part
> separately; this naturally adds more value to the other proposal.

Just adding a note about that, while I don't forget about it
(apologies for the short digression..).

pgstat_dsa_init_size() currently documents the following thing:
/*
* The size of the shared memory allocation for stats stored in the shared
* stats hash table. This allocation will be done as part of the main shared
* memory, rather than dynamic shared memory, allowing it to be initialized in
* postmaster.
*/

Switching pgstats to use the DSM registry would imply a
dsa_create_ext(), that cannot happen in the postmaster (assert in
dsm.c), hence a DSM registry call in pgstat_initialize(). I think
that this initial idea may lack robustness, because we would delay the
pgstats initialization to happen later, at the first BaseInit() rather
than have the postmaster do the basics. I haven't looked at how this
idea would bundle with the single user mode, but I'd feel that pgstats
may break also in this case.
--
Michael