From: Kyotaro Horiguchi <horikyota....@gmail.com> > Another reason that I mildly want to object to subdivided functions is > I was annoyed that a stats view makes many individual calls to > functions that internally share the same statistics entry. That > behavior required me to provide an entry-caching feature to my > shared-memory statistics patch.
+1 The views for troubleshooting performance problems should be as light as possible. IIRC, we saw frequently searching pg_stat_replication consume unexpectedly high CPU power, because it calls pg_stat_get_activity(null) to get all sessions and join them with the walsenders. At that time, we had hundreds of client sessions. We expected pg_stat_replication to be very lightweight because it provides information about a few walsenders. Regards Takayuki Tsunakawa
