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Displaying posts with tag: Online Schema Change (reset)
Galera Cluster: adding a primary key to a MySQL table which lacks it... without downtime

OK, let me start with saying that a table without a primary key shouldn't be something that a DBA should ever stumble into.  Sure, InnoDB will secretly add one for us without telling - but that's not something we can use at application or administration level, it's just to make the engine happy.

So let's suppose you find some tables that lack a primary key, of course you need to do something about it, right?  Now, put Galera Cluster in the mix - Galera does not support tables without a primary key and will, secretly again, make that table inconsistent at cluster level.

You need to fix the damn table(s)!! And this is where the fun begins...  as you can't afford downtime for the operation so you need to resort to an online schema change of some type.

Galera cluster is …

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