Re: [Maria-discuss] Replication New to Old

2018-04-05 Thread Bruce Carlson
Hi Michael,

I tried this when 10.1 first came out with a daisy chain replication system but 
couldn't get it working so upgraded all of my five sites to 10.1
The upgrade proved easy and took less time then I spent trying to get the mixed 
version replicator to work.

Bruce Carlson


-Original Message-
From: Maria-discuss 
[mailto:maria-discuss-bounces+bruce.carlson=nepean@lists.launchpad.net] On 
Behalf Of Reindl Harald
Sent: Friday, 6 April 2018 5:17 AM
To: maria-discuss@lists.launchpad.net
Subject: Re: [Maria-discuss] Replication New to Old



Am 05.04.2018 um 20:22 schrieb Michael Caplan:
> I realize that in general replication from a newer master to an older 
> slave is typically not recommended.  This said, does anyone have an 
> experience replicating from MariaDB 10.2 to MySQL 5.6?
> 
> The compatibility matrix found here:
> https://mariadb.com/kb/en/library/mariadb-vs-mysql-compatibility/ 
> Seems to be missing data on this type of setup
i bet nobody does that because it's a long known fact that a newer version 
might write statements into the binlog the older slave don't understand - that 
can happen at any point in time breaking replication silently

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Re: [Maria-discuss] Replication New to Old

2018-04-05 Thread Kristian Nielsen
andrei.el...@pp.inet.fi writes:

> Mike,
>
>> Hello,
>>
>> I realize that in general replication from a newer master to an older
>> slave is typically not recommended.  This said, does anyone have an
>> experience replicating from MariaDB 10.2 to MySQL 5.6?
>
> A problem that is evident at once is 10.2 GTID events can not be handled
> by 5.6. So at least some filtering should be devised.

10.2 does not send GTID to a slave that does not understand it (they are
rewritten on-the-fly to BEGIN query events). So GTID events should not cause
5.6 slave to break.

More generally, the code in MariaDB (at least the code that I wrote) detects
what capabilities the slave has, and avoids sending stuff from the master
that an old slave will not understand. See MARIA_SLAVE_CAPABILITY_* in
log_event.h.

So the intention is that replication to old slave should work. However, this
still requires that applications restrict themselves from using any SQL not
supported on the old slave. And it is only poorly tested, if at all. Hence
the recommendation to avoid new master->old slave.

Hope this helps,

 - Kristian.

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Re: [Maria-discuss] Replication New to Old

2018-04-05 Thread andrei . elkin
Mike,

> Hello,
>
> I realize that in general replication from a newer master to an older
> slave is typically not recommended.  This said, does anyone have an
> experience replicating from MariaDB 10.2 to MySQL 5.6?

A problem that is evident at once is 10.2 GTID events can not be handled
by 5.6. So at least some filtering should be devised.
To that part, maybe

 mysqlbinlog --read-from-remote-server=10.2-"master" | filter | mysql-client-to 
5.6-"slave"

could be practical?


>
> The compatibility matrix found here:
> https://mariadb.com/kb/en/library/mariadb-vs-mysql-compatibility/
> Seems to be missing data on this type of setup.
>

True. Cross-vendor replication check is very involving.

>
> Thanks,
>
> Mike

Cheers,

Andrei



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Re: [Maria-discuss] Replication New to Old

2018-04-05 Thread Reindl Harald


Am 05.04.2018 um 20:22 schrieb Michael Caplan:
> I realize that in general replication from a newer master to an older
> slave is typically not recommended.  This said, does anyone have an
> experience replicating from MariaDB 10.2 to MySQL 5.6?
> 
> The compatibility matrix found here:
> https://mariadb.com/kb/en/library/mariadb-vs-mysql-compatibility/ Seems
> to be missing data on this type of setup
i bet nobody does that because it's a long known fact that a newer
version might write statements into the binlog the older slave don't
understand - that can happen at any point in time breaking replication
silently

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