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Re: Ideas for improving MariaDB/MySQL replication



On Wed, 19 May 2010 15:05:55 +0200, Sergei Golubchik <serg@xxxxxxxxxxxx>
> Yes, it only describes how the data get to the redundancy service, but
> not what happens there. I intentionally kept the details of redundancy
> out, to be able to satisfy a wide range of different implementations.
> For example, if I'd put a global transaction ID explicitly in the model,
> then MySQL replication would not fit into it - it has such a concept
> only implicitly, as you have noted.
> So, what I did was, as Robert Hodges put it, "pushed the can down the
> road", and let the redundancy service to take care of the transaction
> ids.
> But perhaps I'm biased and the model I've described is influenced by
> MySQL replication more than it should've been ?
Oh, not really. I just wanted to note that while you were proposing a
useful framework, you did not touch actual replication/redundancy

Speaking of current MySQL replication, I was skeptical from the beginning
that it will fit into new redundancy service in its current unmodified
form. It is simply too integrated with the server for that (just think of
all those HAVE_REPLICATION ifdefs). That's why I proposed to keep them side
by side and not try to unify them.

It would be a shame to adapt new replication architecture to existing
MySQL replication. I believe it should go the other way around. And
seriously, mapping an integer to a file offset is a student's play and is a
minor tweak compared to making MySQL replication a module of a new
redundancy service. So it is just a matter of administrative decision -
will _MariaDB_ replication have explicit global transaction IDs or not.

Alexey Yurchenko,
Codership Oy, www.codership.com
Skype: alexey.yurchenko, Phone: +358-400-516-011

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