XA Transaction

    After XAShardingSphereTransactionManager register the corresponding XAResource to the current XA transaction, transaction manager will send XAResource.start command to databases. After databases received XAResource.end command, all SQL operator will mark as XA transaction.

    and sql2 in example will be marked as XA transaction.

    For example:

    1. XAResource2.prepare           ## ack: yes
    3. XAResource2.commit
    4. XAResource1.prepare           ## ack: yes
    5. XAResource2.prepare           ## ack: no
    6. XAResource1.rollback