MySQL Cluster Limitations

The following limitations apply to MySQL clusters consisting of two or more virtual machines:

  • replication works only with the InnoDB storage engine (MyISAM is not supported);
  • ALTER TABLE can stop the cluster, we recommend using the pt-online-schema-change utility;
  • LOCK/UNLOCK, GET_LOCK()/RELEASE_LOCK() queries are not supported;
  • all tables must have a primary key, otherwise it will be impossible to write (INSERT);
  • XA transactions are not supported due to possible rollback on COMMIT;
  • a transaction can rollback even after the COMMIT — there can be two transactions changing the same record in different nodes, and only one of them will successfully commit. The other one will be aborted at the cluster level;
  • avoid reusing the names of persistent tables for temporary tables. If such a match occurs, the replication of the persistent table is blocked.

Learn more about limitations in the official Percona XtraDB Cluster documentation.