> On Mon, Aug 11, 2014 at 9:23 AM, Tatsuo Ishii <is...@postgresql.org> wrote: >> We can know the LSN of last committed WAL record on primary by using >> pg_current_xlog_location(). It seems there's no API to know the time >> when the WAL record was created. I would like to know standby delay by >> using pg_last_xact_replay_timestamp() and such that API. >> >> If there's no such a API, it would be useful to invent usch an API IMO. > > +1 > > I proposed that function before, but unfortunately it failed to be applied. > But I still think that function is useful to calculate the replication delay. > The past discussion is > http://www.postgresql.org/message-id/cahgqgwf3zjfunej5ka683ku5rqubtswtqfq7g1x0g34o+jx...@mail.gmail.com
I looked into the thread briefly and found Simon and Robert gave -1 for this because of performance concern. I'm not sure if it's a actual performance penalty or not. Maybe we need to major the penalty? However I still think that kind of API is very useful because replication delay is one of the big DBA's concern. Why don't we have a switch to enable the API for DBAs who think the priority is replication delay, over small performance penalty? Best regards, -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese:http://www.sraoss.co.jp -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
