#include <db_cxx.h> int DbEnv::add_data_dir(const char *dir);
Add 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 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 "add_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 "add_data_dir" parameter in it.
The DbEnv::add_data_dir()
method configures operations performed
using the specified DbEnv
handle, not all operations performed on the underlying database environment.
The DbEnv::add_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::add_data_dir()
must be consistent
with the existing environment or corruption can occur.
The DbEnv::add_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::add_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.