At Tue, 10 Dec 2019 00:44:09 +0100, Tomas Vondra <tomas.von...@2ndquadrant.com> wrote in > Hi, > > I think there's a minor bug in pg_stat_activity tracking of walsender > processes. The issue is that xact_start is only updated at the very > beginning when the walsender starts (so it's almost exactly equal to > backend_start) and then just flips between NULL and that value. > > Reproducing this is trivial - just create a publication/subscription > with the built-in logical replication, and run arbitrary workload. > You'll see that the xact_start value never changes. > > I think the right fix is calling SetCurrentStatementStartTimestamp() > right before StartTransactionCommand() in ReorderBufferCommit, per the > attached patch.
I'm not sure how much xact_start for walsender is useful and we really is not running a statement there. Also autovac launcher starts transaction without a valid statement timestamp perhaps for the same reason. However, if we want to show something meaningful there, I think commit_time might be more informative there. If we use GetCurrentTimestamp(), StartTransaction() already has the same feature for autonomous transactions. I suppose we should do them a unified way. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
