On Thu, 17 Nov 2016 08:26:59 -0900 Israel Brewster <israel@xxxxxxxxxxxxxx> wrote: > > On Nov 16, 2016, at 4:24 PM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> > > wrote: > > > > On 11/16/2016 04:51 PM, Israel Brewster wrote: > >> I've been playing around with streaming replication, and discovered that > >> the following series of steps *appears* to work without complaint: > >> > >> - Start with master on server A, slave on server B, replicating via > >> streaming replication with replication slots. > >> - Shut down master on A > >> - Promote slave on B to master > >> - Create recovery.conf on A pointing to B > >> - Start (as slave) on A, streaming from B > >> > >> After those steps, A comes up as a streaming replica of B, and works as > >> expected. In my testing I can go back and forth between the two servers > >> all day using the above steps. > >> > >> My understanding from my initial research, however, is that this > >> shouldn't be possible - I should need to perform a new basebackup from B > >> to A after promoting B to master before I can restart A as a slave. Is > >> the observed behavior then just a "lucky fluke" that I shouldn't rely > > > > You don't say how active the database is, but I going to say it is not > > active enough for the WAL files on B to go out for scope for A in the time > > it takes you to do the switch over. > > Yeah, not very - this was just in testing, so essentially no activity. So > between your response and the one from Jehan-Guillaume de Rorthais, what I'm > hearing is that my information about the basebackup being needed was > obsoleted with the patch he linked to, and as long as I do a clean shutdown > of the master, and don't do too much activity on the *new* master before > bringing the old master up as a slave (such that WAL files are lost) Just set up wal archiving to avoid this (and have PITR backup as a side effect). -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
