Re: Add a GUC check hook to ensure summarize_wal cannot be enabled when wal_level is minimal

On Mon, Jul 15, 2024 at 2:47 PM Nathan Bossart <nathandbossart@gmail.com> wrote:
> My understanding is that the correctness of this GUC check hook depends on
> wal_level being a PGC_POSTMASTER GUC.  The check hook would always return
> true during startup, and there'd be an additional cross-check in
> PostmasterMain() that would fail startup if necessary.  After that point,
> we know that wal_level cannot change, so the GUC check hook for
> summarize_wal can depend on wal_level.  If it fails, my expectation would
> be that the server would just ignore that change and continue.

But how do you know that, during startup, the setting for
summarize_wal is processed after the setting for wal_level?

--
Robert Haas
EDB: http://www.enterprisedb.com