On Sat, Nov 6, 2010 at 3:46 AM, Josh Berkus <j...@agliodbs.com> wrote: > I'm continuing in my efforts now to document how to deploy and manage > replication on our wiki. One of the things a DBA needs to do is to use > pg_current_xlog_location() (and related functions) to check how far > behind the master the standby is. > > However, there's some serious problems with that: > > (1) comparing these numbers is quite mathematically complex -- and, for > that matter, undocumented. > > (2) pg_rotate_xlog and/or archive_timeout will create a "gap" in the > xlog positions, quite a large one if it happens near the beginning of a > file. There is no way for any monitoring on the standby to tell the > difference between a gap created by forced rotation as opposed to being > most of a file behind, until the next record shows up. Hello, nagios > false alerts! > > (3) There is no easy way to relate a difference in log positions to an > amount of time.
The patch which I'm proposing is helpful for you? http://archives.postgresql.org/pgsql-hackers/2010-11/msg00167.php Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
