- Berkeley DB Reference Guide:
- Berkeley DB Replication
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Base replication API
Applications which use the Base replication API use the following
Berkeley DB methods.
- DB_ENV->rep_set_transport
- The DB_ENV->rep_set_transport method configures the replication system's
communications infrastructure.
- DB_ENV->rep_start
- The DB_ENV->rep_start method configures (or reconfigures) an existing database
environment to be a replication master or client.
- DB_ENV->rep_process_message
- The DB_ENV->rep_process_message method is used to process incoming messages from other
environments in the replication group. For clients, it is responsible
for accepting log records and updating the local databases based on
messages from the master. For both the master and the clients, it is
responsible for handling administrative functions (for example, the
protocol for dealing with lost messages), and permitting new clients to
join an active replication group. This method should only be called
after the environment has been configured as a replication master or
client via DB_ENV->rep_start.
- DB_ENV->rep_elect
- The DB_ENV->rep_elect method causes the replication group to elect a new
master; it is called whenever contact with the master is lost and the
application wants the remaining sites to select a new master.
- DB_ENV->set_event_notify
- The DB_ENV->set_event_notify method is needed for applications to
discover important replication-related events, such as the result of
an election and appointment of a new master.
- DB_ENV->rep_set_priority
- The DB_ENV->rep_set_priority method configures the local site's priority for
the purpose of elections.
- DB_ENV->rep_set_timeout
- Note that of all the various timeouts this method can set, only
DB_REP_ELECTION_TIMEOUT is relevant for applications which use
the Base replication API. The others are used only by Replication
Manager.
- DB_ENV->rep_set_limit
- The DB_ENV->rep_set_limit method imposes an upper bound on the amount of data
that will be sent in response to a single call to DB_ENV->rep_process_message.
During client recovery, that is, when a replica site is trying to
synchronize with the master, clients may ask the master for a large
number of log records. If it is going to harm an application for the
master message loop to remain busy for an extended period transmitting
records to the replica, then the application will want to use
DB_ENV->rep_set_limit to limit the amount of data the master will send
before relinquishing control and accepting other messages.
In addition to the methods previously described, applications which use
the Base replication API may also call the following methods, as needed:
DB_ENV->rep_stat, DB_ENV->rep_sync, DB_ENV->rep_set_config.
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