Set the path of a directory to be used as the location of the access
method database files. Paths specified to the Db::open function
will be searched relative to this path. Paths set using this interface
are additive, and specifying more than one will result in each specified
directory being searched for database files. If any directories are
specified, created database files will always be created in the first path
specified.
If no database directories are specified, database files can only exist
in the environment home directory. See Berkeley DB File Naming for more information.
For the greatest degree of recoverability from system or application
failure, database files and log files should be located on separate
physical devices.
The DbEnv::set_data_dir interface may only be used to configure Berkeley DB before
the DbEnv::open interface is called.
The DbEnv::set_data_dir 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.
The database environment's data directory may also be set using the environment's
DB_CONFIG file. The syntax of the entry in that file is a
single line with the string "set_data_dir", one or more whitespace characters,
and the directory name. Because the DB_CONFIG file is read when the database
environment is opened, it will silently overrule configuration done
before that time.