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Re: ee538938345: MDEV-21117: refine the server binlog-based recovery for semisync


Hi, Andrei!

On Mar 24, Andrei Elkin wrote:
> >> Here it goes.
> >> 
> >> As after master crash and failover to slave, the demoted-to-slave
> >> ex-master must be ready to face and accept its own (generated by)
> >> events, without generally necessary --replicate-same-server-id.
> >> 
> >> So the acceptance conditions are refined/relaxed for the semisync
> >> slave connected to master in the GTID mode which ensures (under
> >> gtid_strict_mode ON) that there can't be any duplicate events for
> >> execution on such an ex-master slave. Non-GTID "binlog-truncated"
> >> ex-master semisync slave has to be configured with
> >> --replicate-same-server-id.
> >
> > Why would you generally care about same server id in the gtid mode?
> Maybe you did not care in above to the 'connection' word in 'the gtid
> connection mode' which is about
>  Change-Master to ... master_use_gtid= slave_pos
> So the "legacy" pre-gtid one corresponds to master_use_gtid= no.
> [Thinking into future, it may stay for some more time actually to
> serve for manual recovery of the slave.]

As discussed on slack, let's now only support fully automatic recovery
for the case of master_use_gtid=slave_pos.

If one uses master_use_gtid=none the failover is non-trivial anyway.
We can always add flipping of replicate-same-server-id later, if needed.

VP of MariaDB Server Engineering
and security@xxxxxxxxxxx