> On Nov 16, 2016, at 4:24 PM, Adrian Klaver <adrian.kla...@aklaver.com> 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), then the above failover/failback procedure is perfectly fine to rely on in production - I don't have to worry about there being any hidden gotchas like the new slave not *really* replicating or something. Thanks! ----------------------------------------------- Israel Brewster Systems Analyst II Ravn Alaska 5245 Airport Industrial Rd Fairbanks, AK 99709 (907) 450-7293 ----------------------------------------------- > >> on? Or is it expected behavior and my understanding about the need for a >> new basebackup is simply off? Does the new pg_rewind feature of 9.5 >> change things? If so, how? >> >> Thanks for your time! >> ----------------------------------------------- >> Israel Brewster >> Systems Analyst II >> Ravn Alaska >> 5245 Airport Industrial Rd >> Fairbanks, AK 99709 >> (907) 450-7293 >> ----------------------------------------------- >> >> >> >> >> > > > -- > Adrian Klaver > adrian.kla...@aklaver.com <mailto:adrian.kla...@aklaver.com> > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org > <mailto:pgsql-general@postgresql.org>) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > <http://www.postgresql.org/mailpref/pgsql-general>
