Re: pg_stat_statements stores WITH HOLD cursor query with literals

On Thu, Oct 22, 2026 at 12:09:56PM +0900, Michael Paquier wrote:
> We have a similar concept for ExplainState with its extension_state
> indexed by GetExplainExtensionId() based on an extension name.
> Perhaps we should do something similar for QueryDesc? That would take
> care of the conflicting states across extensions at least, giving
> extensions way to store in the QueryDesc what they want. Here, that's
> the nesting_level that you want to track *only* in PGSS and have no
> other extensions meddle with it.

This was itching me, so I have looked at what it would look like,
finishing with the attached set of two patches:
- One to introduce a backend-side facility to give for extensions a
way to plug in custom data into QueryDesc.
- The second patch is a refactored v2, that makes use of the new
infra.

That feels rather neat. This facility could be extended to other
things, like auto_explain perhaps?
--
Michael