Hi Thomas. At 2017-02-15 00:48:41 +1300, thomas.mu...@enterprisedb.com wrote: > > Here is a new version with the buffer on the sender side as requested.
This looks good. > + <entry><structfield>write_lag</></entry> > + <entry><type>interval</></entry> > + <entry>Estimated time taken for recent WAL records to be written on this > + standby server</entry> I think I would find a slightly more detailed explanation helpful here. A few tiny nits: > + * If the lsn hasn't advanced since last time, then do nothing. This > way > + * we only record a new sample when new WAL has been written, which is > + * simple proxy for the time at which the log was written. "which is simple" → "which is a simple" > + * If the buffer if full, for now we just rewind by one slot and > overwrite > + * the last sample, as a simple if somewhat uneven way to lower the > + * sampling rate. There may be better adaptive compaction algorithms. "buffer if" → "buffer is" > + * Find out how much time has elapsed since WAL position 'lsn' or earlier was > + * written to the lag tracking buffer and 'now'. Return -1 if no time is > + * available, and otherwise the elapsed time in microseconds. Find out how much time has elapsed "between X and 'now'", or "since X". (I prefer the former, i.e., s/since/between/.) -- Abhijit -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers