DbEnv::rep_set_config()
Prev | Chapter 11. Replication Methods | Next

## DbEnv::rep_set_config()

    #include <db_cxx.h>

    int
    DbEnv::rep_set_config(u_int32_t which, int onoff);

The `DbEnv::rep_set_config()` method configures the Berkeley DB replication subsystem.

The database environment's replication subsystem may also be configured using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "rep_set_config", one or more whitespace characters, and the method which parameter as a string; for example, "rep_set_config DB_REP_CONF_NOWAIT". Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

The `DbEnv::rep_set_config()` method configures a database environment, not only operations performed using the specified DbEnv handle.

The `DbEnv::rep_set_config()` method may not be called to set in-memory replication after the environment is opened using the DbEnv::open() method. This method may also not be called to set master leases after the DbEnv::rep_start() or DbEnv::repmgr_start() methods are called. For all other which parameters, this method may be called at any time during the life of the application.

The `DbEnv::rep_set_config()` method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

### Parameters

#### onoff

If the onoff parameter is zero, the configuration flag is turned off. Otherwise, it is turned on. All configuration flags are turned off by default.

#### which

The which parameter must be set to one of the following values:

- `DB_REP_CONF_BULK`

  The replication master sends groups of records to the clients in a single network transfer.

- `DB_REP_CONF_DELAYCLIENT`

  The client should delay synchronizing to a newly declared master. Clients configured in this way will remain unsynchronized until the application calls the DbEnv::rep_sync() method.

- `DB_REP_CONF_INMEM`

  Store internal replication information in memory only.

  By default, replication creates files in the environment home directory to preserve some internal information. If this configuration flag is turned on, replication only stores this internal information in-memory and cannot keep persistent state across a site crash or reboot. This results in the following limitations:

  - A master site should not reappoint itself master immediately after crashing or rebooting because the application would incur a slightly higher risk of client crashes. The former master site should rejoin the replication group as a client. The application should either hold an election or appoint a different site to be the next master.

  - An application has a slightly higher risk that elections will fail or be unable to complete. Calling additional elections should eventually yield a winner.

  - An application has a slight risk that the wrong site may win an election, resulting in the loss of some data. This is consistent with the general loss of data durability when running in-memory.

  This configuration flag can only be turned on before the environment is opened with the DbEnv::open() method. Its value cannot be changed while the environment is open.

- `DB_REP_CONF_LEASE`

  Master leases will be used for this site.

  Configuring this option may result in `DB_REP_LEASE_EXPIRED` error returns from the Db::get() and Dbc::get() methods when attempting to read entries from a database after the site's master lease has expired.

  This configuration flag may not be set after the DbEnv::repmgr_start() method or the DbEnv::rep_start() method is called.

- `DB_REP_CONF_NOAUTOINIT`

  The replication master will not automatically re-initialize outdated clients.

- `DB_REP_CONF_NOWAIT`

  Berkeley DB method calls that would normally block while clients are in recovery will return errors immediately.

- `DB_REPMGR_CONF_2SITE_STRICT`

  Replication Manager observes the strict "majority" rule in managing elections, even in a group with only 2 sites. This means the client in a 2-site group will be unable to take over as master if the original master fails or becomes disconnected. (See the Elections section in the Berkeley DB Programmer's Reference Guide for more information.) Both sites in the replication group should have the same value for this configuration flag.

### Errors

The `DbEnv::rep_set_config()` method may fail and throw a DbException exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

#### EINVAL

If setting in-memory replication after the database environment is already opened; if setting master leases after replication is started; if setting the 2-site strict majority rule for a Base API application; or if an invalid flag value or parameter was specified.

### Class

DbEnv

### See Also

Replication and Related Methods

Prev | Up | Next
DbEnv::rep_set_clockskew() | Home | DbEnv::rep_set_limit()