#include <db_cxx.h> int DbEnv::set_data_dir(const char *dir);
This interface has been deprecated. You should use DbEnv::add_data_dir() and DbEnv::set_create_dir() instead.
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 method are additive, and specifying more than one will result in each specified directory being searched for database files. If any directories are specified, database files will always be created in the first path specified.
If no database directories are specified, database files must be named either by absolute paths or relative to the environment home directory. See Berkeley DB File Naming for more information.
The database environment's data directories 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 "set_data_dir", one or more whitespace characters, and the directory name. Note that if you use this method for your application, and you also want to use the db_recover or db_archive utilities, then you should create a DB_CONFIG file and set the "set_data_dir" parameter in it.
         The DbEnv::set_data_dir() method
         configures operations performed using the specified 
         DbEnv  handle, not all operations
         performed on the underlying database environment.
    
         The DbEnv::set_data_dir() method may not
         be called after the 
         DbEnv::open()  method is
         called.  If the database environment already exists when 
         DbEnv::open()  is called, the
         information specified to
         DbEnv::set_data_dir() must be consistent
         with the existing environment or corruption can occur.
    
         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 dir parameter is a directory to be used as a location for database files. This directory must currently exist at environment open time.
When using a Unicode build on Windows (the default), this argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.
             The DbEnv::set_data_dir() 
            
            
                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:
            
        
        
If the method was called after DbEnv::open() was called; or if an invalid flag value or parameter was specified.