Transactions and queries during SST

[Ramiz]

I have two node galera cluster(say node1, node2, grabd) on my servers, No haproxy. Clusters sharing load of two separate java application with a single database.

In my case i am going migrate 1Tb of mysql data using innobackupex from a legacy server to a cluster node1. So my question is, will the SST fails on node2, if i suppose to do transactions/queries like insert,delete,alter on node1 during the time of SST on node2.

Thanks in advance.

[Philip Stoev]

Hello,

You can run insert and update statements on node 1 after the import is done
and while the SST to node 2 is in progress if you are using xtrabackup-v2 as
your SST method. If rsync or mysqldump are used for SST, the donor, node 1,
will be blocked for the duration.

Running ALTER during xtrabackup SST should work however is not recommended.
An ALTER statement in progress can cause the SST to block and wait until it
is complete. It is best to have the tables in their final form before
attempting to join node 2.

Thank you.

Philip Stoev

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[Ramiz]

I appreciate your quick and detailed response.

I am using rsync as the default method. If I suppose to wait till the node2 gets in sync, it will affect my websites traffic. Is there anyway to update node2 with less delay.

[Philip Stoev]

Hello,

The safest and easiest option that allows node1 to accept queries while it
is providing SST to node2 is to use xtrabackup-v2 as the SST method.

[James Wang]

Thought rsync is now the default Galera recommended SST

[alexey.y...@galeracluster.com]

On 2015-11-06 10:22, James Wang wrote:
> Thought rsync is now the default Galera recommended SST

It is not "recommended". It is the "default". Different users may have
different experience.