Hi, On Mon, 10 Mar 2025 at 17:43, Bertrand Drouvot <bertranddrouvot...@gmail.com> wrote: > On Mon, Mar 10, 2025 at 03:08:49PM +0300, Nazir Bilal Yavuz wrote: > > > I think that every time we flush IO or WAL stats, we want(?) to flush > > backend stats as well, > > Yeah, I think that's happening anyway. > > > so would it make sense to move > > pgstat_flush_backend() calls to inside of pgstat_flush_io() and > > pgstat_wal_flush_cb()? > > I don't think so because pgstat_flush_backend() still needs to be called by > the > pgstat_backend_flush_cb() (i.e flush_static_cb) callback (I mean I think this > makes sense to keep this callback around and that it does "really" something). > > So for example, for the WAL case, that would mean the backend WAL stats would > be > flushed twice: one time from pgstat_wal_flush_cb() (i.e flush_static_cb) > callback > and one time from the pgstat_backend_flush_cb() (another flush_static_cb) > callback. > > I think it's better to keep them separate and reason as they are distinct > types of stats (which they really are). I think we had the same kind of > reasoning > while working on [1].
I got it, that makes sense. Thanks for the explanation. > > I see that backend statistics are not collected > > for some of the backend types but that is already checked in the > > pgstat_flush_backend() with pgstat_tracks_backend_bktype(). > > Sorry, I don't get it. Do you have a question around that? Sorry for the confusion. I did not think of the explanation that you did above. I was thinking that we do not want to call pgstat_flush_backend(.., PGSTAT_BACKEND_FLUSH_IO) for the (let's say) checkpointer as its backend statistics are not collected and that is the reason why we do not want to put pgstat_flush_backend() inside of pgstat_flush_io(). Your explanation made it clear now, no other questions. -- Regards, Nazir Bilal Yavuz Microsoft
