maria-discuss team mailing list archive

["Mark Wadham" <ubuntu@xxxxxx>]

Hi Nirbhay,

> As discussed on IRC #mariadb, you do not really need to take the node 
> off
> cluster (3).
> Just set wsrep_osu_method's session value to RSU and perform the 
> schema
> change.
> With RSU mode enabled, the node automatically desyncs itself from the
> cluster before
> executing any DDL,and thus other nodes in the cluster are not 
> impacted.

I don't think this was the case during our testing, but I'll test it 
again anyway.  If I understand RSU mode correctly all it does is ensure 
that DDL statements aren't replicated to the other nodes.  AFAIK it 
won't stop the write events from the other nodes from being synced to 
the node in RSU mode, meaning that if we have writes to the table being 
altered we could run into problems.  We have some very large tables and 
one of them we tested took around 7h 45min to add a column.

Mark