On Tue, Dec 21, 2021 at 8:32 PM Melanie Plageman <melanieplage...@gmail.com> wrote: > On Thu, Dec 16, 2021 at 3:18 PM Andres Freund <and...@anarazel.de> wrote: > > > > > From 9f22da9041e1e1fbc0ef003f5f78f4e72274d438 Mon Sep 17 00:00:00 2001 > > > > > From: Melanie Plageman <melanieplage...@gmail.com> > > > > > Date: Wed, 24 Nov 2021 12:20:10 -0500 > > > > > Subject: [PATCH v17 6/7] Remove superfluous bgwriter stats > > > > > > > > > > Remove stats from pg_stat_bgwriter which are now more clearly > > > > > expressed > > > > > in pg_stat_buffers. > > > > > > > > > > TODO: > > > > > - make pg_stat_checkpointer view and move relevant stats into it > > > > > - add additional stats to pg_stat_bgwriter > > > > > > > > When do you think it makes sense to tackle these wrt committing some of > > > > the > > > > patches? > > > > > > Well, the new stats are a superset of the old stats (no stats have been > > > removed that are not represented in the new or old views). So, I don't > > > see that as a blocker for committing these patches. > > > > > Since it is weird that pg_stat_bgwriter had mostly checkpointer stats, > > > I've edited this commit to rename that view to pg_stat_checkpointer. > > > > > I have not made a separate view just for maxwritten_clean (presumably > > > called pg_stat_bgwriter), but I would not be opposed to doing this if > > > you thought having a view with a single column isn't a problem (in the > > > event that we don't get around to adding more bgwriter stats right > > > away). > > > > How about keeping old bgwriter values in place in the view , but generated > > from the new stats stuff? > > I tried this, but I actually don't think it is the right way to go. In > order to maintain the old view with the new source code, I had to add > new code to maintain a separate resets array just for the bgwriter view. > It adds some fiddly code that will be annoying to maintain (the reset > logic is confusing enough as is). > And, besides the implementation complexity, if a user resets > pg_stat_bgwriter and not pg_stat_buffers (or vice versa), they will > see totally different numbers for "buffers_backend" in pg_stat_bgwriter > than shared buffers written by B_BACKEND in pg_stat_buffers. I would > find that confusing.
In a quick chat off-list, Andres suggested it might be okay to have a single reset target for both the pg_stat_buffers view and legacy pg_stat_bgwriter view. So, I am planning to share a new patchset which has only the new "buffers" target which will also reset the legacy pg_stat_bgwriter view. I'll also remove the bgwriter stats I proposed and the pg_stat_checkpointer view to keep things simple for now. - Melanie