At any time, you can transform the
database that has the
slave role into a normal
database that can
process transactions. This transformation from being a slave to becoming an
active database is
called failover. During failover, the slave applies the parts of the
transaction log that have not yet been processed. It then undoes operations that
belong to uncommitted transactions, resulting in a transaction-consistent state
that includes all transactions whose commit log record has been sent to the
slave.
You perform failover from the master system. To do so, you connect to the
database on the master system using
the failover=true connection URL attribute. For example, for a database
named wombat, you might specify the following connection URL:
jdbc:derby:wombat;failover=true
If the network connection between the master system and the slave system is
lost, you can perform failover from the slave system.
See the for details about the
failover=true attribute.
There is no automatic failover or restart of replication after one of the
instances has failed.