int DB_ENV->set_data_dir(DB_ENV *dbenv, const char *dir);
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 exist only 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 DB_ENV->set_data_dir method configures operations performed using the specified DB_ENV handle, not all operations performed on the underlying database environment.
The DB_ENV->set_data_dir interface may not be called after the DB_ENV->open interface is called. If the database environment already exists when DB_ENV->open is called, the information specified to DB_ENV->set_data_dir must be consistent with the existing environment or corruption can occur.
The DB_ENV->set_data_dir method returns a non-zero error value on failure and 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.
The DB_ENV->set_data_dir method may fail and return a non-zero error for the following conditions:
Called after DB_ENV->open was called.
The DB_ENV->set_data_dir method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB_ENV->set_data_dir method may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.
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