At Fri, 18 Sep 2020 09:40:11 +0900, Masahiro Ikeda <ikeda...@oss.nttdata.com> wrote in > Thanks. I confirmed that it causes HOT pruning or killing of > dead index tuple if DecodeCommit() is called. > > As you said, DecodeCommit() may access the system table. ... > The wals are generated only when logical replication is performed. > So, I added pgstat_send_wal() in XLogSendLogical(). > > But, I concerned that it causes poor performance > since pgstat_send_wal() is called per wal record,
I think that's too frequent. If we want to send any stats to the collector, it is usually done at commit time using pgstat_report_stat(), and the function avoids sending stats too frequently. For logrep-worker, apply_handle_commit() is calling it. It seems to be the place if we want to send the wal stats. Or it may be better to call pgstat_send_wal() via pgstat_report_stat(), like pg_stat_slru(). Currently logrep-laucher, logrep-worker and autovac-launcher (and some other processes?) don't seem (AFAICS) sending scan stats at all but according to the discussion here, we should let such processes send stats. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
