On Sat, Mar 12, 2016 at 3:10 AM, Andres Freund <andres@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.
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.
From the DBA point of view it is much more convenient to see all wait events in one view. I don’t know if it is right to break compability even more, but IMHO exposing this data in different views is a bad plan.
Do you intend to get this done for 9.6 considering an add-on patch for wait event information displayed in pg_stat_activity?