From: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> |
---|---|
To: | Israel Brewster <israel(at)ravnalaska(dot)net>, "pgsql-general(at)postgresql(dot)org general" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Streaming replication failover/failback |
Date: | 2016-11-17 01:24:44 |
Message-ID: | 4d716d32-e396-e331-e26e-efd42f7a02dd@aklaver.com |
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Lists: | pgsql-general |
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.
> 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(dot)klaver(at)aklaver(dot)com
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