Hi, On Wed, Jul 8, 2009 at 4:00 AM, Heikki Linnakangas<heikki.linnakan...@enterprisedb.com> wrote: >> I would envision the slaves >> connecting to the master's replication port and asking "feed me WAL >> beginning at LSN position thus-and-so", with no notion of WAL file >> boundaries exposed anyplace. > > Yep, that's the way I envisioned it to work in my protocol suggestion > that Fujii adopted > (http://archives.postgresql.org/message-id/4951108a.5040...@enterprisedb.com). > The <begin> and <end> values are XLogRecPtrs, not WAL filenames.
If <begin> indicates the middle of the XLOG file, the file written to the standby is partial. Is this OK? After two server failed, the XLOG file including <begin> might still be required for crash recovery of the standby server. But, since it's partial, the crash recovery would fail. I think that any XLOG file should be written to the standby as it can be replayed by a normal recovery. >>The point about not wanting to archive >> lots of WAL on the master would imply that the master reserves the right >> to fail if the requested starting position is too old, whereupon the >> slave needs some way to resync --- but that probably involves something >> close to taking a fresh base backup to copy to the slave. What if the XLOG file required for recovery has gone while doing resync a large data? In this case, the standby might never start because the requested starting position is always too old. 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
