On 2016-03-12 16:29:11 +0530, Amit Kapila wrote: > On Sat, Mar 12, 2016 at 3:10 AM, Andres Freund <and...@anarazel.de> wrote: > > > > > > > Similarly for the wait event stuff - checkpointer, wal writer, > > > background writer are in many cases processes that very often are > > > blocked on locks, IO and such. Thus restricting the facility to > > > database connected processes seems like a loss. > > > > I think one way to address this would be to not only report > > PgBackendStatus type processes in pg_stat_activity. While that'd > > obviously be a compatibility break, I think it'd be an improvement. > > > > I think here another point which needs more thoughts is that many of the > pg_stat_activity fields are not relevant for background processes, ofcourse > one can say that we can keep those fields as NULL, but still I think that > indicates it is not the most suitable way to expose such information.
But neither are all of them relevant for autovacuum workers, and we already show them. pg_stat_activity as a name imo doesn't really imply that it's about plain queries. ISTM we should add a 'backend_type' column that is one of backend|checkpointer|autovacuum|autovacuum-worker|wal writer| bgwriter| bgworker (or similar). That makes querying easier. And then display all shmem connected processes. > Another way could be to have new view like pg_stat_background_activity with > only relevant fields or try expose via individual views like > pg_stat_bgwriter. I think the second is a pretty bad alternative; it'll force us to add new views with very similar information; and it'll be hard to get information about the whole system. I mean if you want to know which locks are causing problems, you don't primarily care whether it's a background process or a backend that has contention issues. > Do you intend to get this done for 9.6 considering an add-on patch for wait > event information displayed in pg_stat_activity? I think we should fix this for 9.6; it's a weakness in a new interface. Let's not yank people around more than we need to. I'm willing to do some work on that, if we can agree upon a course. Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
