On Tue, Dec 10, 2019 at 09:42:17AM +0900, Kyotaro Horiguchi wrote:
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.
Maybe, but then maybe we should change it so that we don't report any
timestamps for such processes.
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.
I don't think so. We have this information from the apply side, and this
is really about the *new* transaction started in reorderbuffer.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
