Galera Cluster and Isolation Levels

[oli.sen...@bluewin.ch]

Hello all,

What InnoDB Isolation Levels is Galera Cluster supporting?

I had something in my mind repeatable-read only
but I am not sure. Can you please clear this?

Could be a candidate for FAQ.

If there is a restriction it would be a
candidate for Limitations.

Regards,
Oli

[seppo....@codership.com]

Locally, in one node, transaction isolation works as with native
InnoDB, so all levels can be used.
But cluster wide, between transactions processing in separate nodes,
Galera implements transaction level called "SNAPSHOT ISOLATION". The
SNAPSHOT ISOLATION level is between REPEATABLE READ and SERIALIZABLE
levels.

SERIALIZABLE level cannot be guaranteed in multi-master use case,
because Galera replication does not carry transaction read set. Also,
SERIALIZABLE transaction is vulnerable for multi-master conflicts. It
holds read locks and any replicated write to read locked row will
cause transaction abort. So you better not use it in Galera Cluster.

-seppo

[Oleksandr Drach]

[Oleksandr Drach]

Hello Oli,

Thanks for your suggestion.

Just updated Galera FAQ with your question.

And Thanks Seppo for posting answer :)

Have a nice clustering!

On Thursday, April 11, 2013 10:45:42 PM UTC+3, shinguz wrote: