Limitations of clusters | Selectel Documentation

Limitations of MySQL sync clusters with replicas

MySQL sync clusters with replicas are subject to restrictions:

replication works only with the storage subsystem InnoDB (MyISAM not supported);
ALTER TABLE may cause the cluster to stop — we recommend using pt-online-schema-change utility;
unsupported requests LOCK/UNLOCK, GET_LOCK()/RELEASE_LOCK();
all tables must have a primary key — otherwise it is impossible to make a record (INSERT);
XA transactions are not supported due to possible ROLLBACK at the stage of COMMIT;
a transaction can be rolled back even after COMMIT — out of two transactions modifying the same record on different nodes, only one will be successfully completed and the other will be aborted at the cluster level;
When naming temporary tables, do not use names that match the names of permanent tables — such a match will stop replication of the permanent table.