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Re: [Commits] Rev 3879: MDEV-6593 : domain_id based replication filters in lp:~maria-captains/maria/maria-10.0-galera



On Mon, Sep 15, 2014 at 10:09 AM, Kristian Nielsen <knielsen@xxxxxxxxxxxxxxx
> wrote:

> Kristian Nielsen <knielsen@xxxxxxxxxxxxxxx> writes:
> > 4. Also see detailed comments for some possible problems with the
> > implementation. The most serious is probably to ensure that events are
> not
> > skipped after the end of the group, we need a couple of tests for this,
> see
> Hm, actually I thought of another potential problem.
> What happens if the slave disconnects from the master in the middle of
> receiving an event group? There are several tricky issues around this part
> of
> replication, we definitely need some test cases for this as well.
> There are different cases, for example whether using GTID or non-GTID mode,
> whether the slave just reconnects, the I/O and/or SQL threads are
> restarted,
> or the entire server restarts. And if the filters are reconfigured before
> reconnecting.

I have tried to add multiple test scenarios to cover these aspects.

> For example, it seems to me that in non-GTID mode, if we restart the
> server in
> the middle of receiving an event group, we can easily end up with ignoring
> one
> half of the group and not the other, which is very bad?

The filtering would only work when slave is configured with GTID.

> And in GTID mode, the reconnect issue is quite tricky also, we need a test
> case to check that everything is ok. Though in this case we always
> reconnect
> at the start of an event group, so maybe things are easier to handle.
> For non-GTID mode, maybe we need to handle the ignoring in the SQL thread
> instead? Or alternatively, we can make ignoring events based on domain_id
> only
> legal in GTID mode, and give an error in non-GTID?

I think the patch follows the 2nd approach minus the error. Could you
please elaborate
on the error?


- Nirbhay