Library Version 18.1.40

DbEnv::cdsgroup_begin()
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## DbEnv::cdsgroup_begin()

    #include <db_cxx.h>

    int
    DbEnv::cdsgroup_begin(DbTxn **tid);

The `DbEnv::cdsgroup_begin()` method allocates a locker ID in an environment configured for Berkeley DB Concurrent Data Store applications. It copies a pointer to a DbTxn that uniquely identifies the locker ID into the memory to which tid refers. Calling the DbTxn::commit() method will discard the allocated locker ID.

See Berkeley DB Concurrent Data Store applications for more information about when this is required.

This method may not be called on a sliced database.

The `DbEnv::cdsgroup_begin()` method may be called at any time during the life of the application.

The `DbEnv::cdsgroup_begin()` 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.

### Errors

The `DbEnv::cdsgroup_begin()` 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 this method is called on a sliced database; or if an invalid flag value or parameter was specified.

#### ENOMEM

The maximum number of lockers has been reached.

### Class

DbEnv, DbTxn

### See Also

Transaction Subsystem and Related Methods

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