From: Lars Thalmann
Date: July 7 2004 10:41am
Subject: Re: Master-Slave Replication with MySQL Cluster
List-Archive: http://lists.mysql.com/cluster/94
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On Mon, 2004-07-05 at 20:07, Thomas Schwanhäuser wrote:
> Is the following possible or does anyone have 
> experience with such a configuration?
> 
> There shall be a Master-Slave replication 
> with around 20 slaves. But in order to have 
> enough "Master" power for replication and
> safe inserts/updates, the Master shall not 
> be a single computer but the whole MySQL Cluster. 
>
> Thus, it's possible to have a cluster 
> replicating to some salves running 
> e.g. MyISAM or InnoDB tables?

Note that the current replication implementation 
catches the queries on the way down through the 
MySQL server and that this has consequences if you
update the same row in two or more MySQL servers in
the same MySQL Cluster (and use replication between
clusters).

The NDB storage engine will make the two updates 
(U1 on MySQL server M1, U2 on MySQL server M2) 
in some order, but the MySQL servers will not 
know the order.  

It can happen that the master MySQL Cluster does 
U1 first and then U2 and that the slave MySQL 
server, or the slave MySQL Cluster first U2 
and then U1.

A solution for this is worked upon, but right now
the fix is to not allow same row to be updated by 
multiple MySQL servers belonging to the same cluster
if one wants replication to work.

Best wishes,
Lars


-- 
Dr. Lars Thalmann
MySQL AB, www.mysql.com
MySQL Cluster, www.mysql.com/cluster