Hi, On 2022-11-15 09:04:25 -0500, Robert Haas wrote: > On Mon, Nov 14, 2022 at 4:17 PM Andres Freund <and...@anarazel.de> wrote: > > Perhaps this would better be tackled by a new "visibility" view. It could > > show > > - number of sessions with a snapshot > > - max age of backend xmin > > - pid with max backend xmin > > - number of sessions that suboverflowed > > - pid of the session with the most subxids > > - age of the oldest prepared xact > > - age of the oldest slot > > - age of the oldest walsender > > - ... > > > > Perhaps implemented in SQL, with new functions for accessing the properties > > we > > don't expose today. That'd address the pg_stat_activity width, while still > > allowing very granular access when necessary. And provide insight into > > something that's way to hard to query right now. > > I wouldn't be against a pg_stat_visibility view, but I don't think I'd > want it to just output a single summary row.
I think it'd be more helpful to just have a single row (or maybe a fixed number of rows) - from what I've observed the main problem people have is condensing the available information, rather than not having information available at all. > I think we really need to > give people an easy way to track down which session is the problem; > the existence of the problem is already obvious from the SLRU-related > wait events. Hence the suggestion to show the pid of the session with the most subxacts. We probably also should add a bunch of accessor functions for people that want more detail... But just seeing in one place what's problematic would be the big get, the rest will be a small percentage of users IME. Greetings, Andres Freund