Hi, On 2019-12-10 00:44:09 +0100, Tomas Vondra wrote: > 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.
> -- > Tomas Vondra http://www.2ndQuadrant.com > PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services > diff --git a/src/backend/replication/logical/reorderbuffer.c > b/src/backend/replication/logical/reorderbuffer.c > index 53affeb877..5235fb31b8 100644 > --- a/src/backend/replication/logical/reorderbuffer.c > +++ b/src/backend/replication/logical/reorderbuffer.c > @@ -1554,7 +1554,10 @@ ReorderBufferCommit(ReorderBuffer *rb, TransactionId > xid, > if (using_subtxn) > BeginInternalSubTransaction("replay"); > else > + { > + SetCurrentStatementStartTimestamp(); > StartTransactionCommand(); > + } I'm quite doubtful this is useful. To me this seems to do nothing but add the overhead of timestamp computation - which isn't always that cheap. I don't think you really can draw meaning from this? Greetings, Andres Freund
