#include <db.h>

int
DB_ENV->set_ext_file_dir(DB_ENV *dbenv, const char *dir);  

The DB_ENV->set_ext_file_dir() method sets the directory where external file data is stored. Use this method when the database is opened within an encompassing environment. If an environment is not in use, use DB->set_ext_file_dir() instead.

By default, if this method is not called then external file data is placed in a subdirectory within the DB's environment.

Once this method has been used, you can call DB_ENV->get_ext_file_dir() to identify the current storage location used for external file data.

This method configures operations performed using the specified DB_ENV handle, not all operations performed on the underlying database environment.

This method may not be called after DB_ENV->open() is called.

Unless otherwise specified, the DB_ENV->set_ext_file_dir() method returns a non-zero error value on failure and 0 on success.