Library Version 18.1.25

DbEnv::set_region_dir()
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## DbEnv::set_region_dir()

    #include <db_cxx.h>

    int
    DbEnv::set_region_dir(const char *dir);

The path of a directory to be used as the location of disk-backed region files. Region files created by the Memory Pool subsystem will be created in this directory.

If no region directory is specified, region files are created in the environment home directory. See Berkeley DB File Naming for more information.

The database environment's region directory 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_region_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. Note that if you use this method for your application, and you also want to use the various utilities like db_recover, then you should set create a DB_CONFIG file and set the "set_region_dir" parameter in it.

The `DbEnv::set_region_dir()` method configures operations performed using the specified DbEnv handle, not all operations performed on the underlying database environment.

The `DbEnv::set_region_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_region_dir()` must be consistent with the existing environment or corruption can occur.

The `DbEnv::set_region_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.

### Parameters

#### dir

The dir parameter is the directory used to store the region files. This directory must currently exist at environment open time.

When using a Unicode build on Windows (the default), the dir argument will be interpreted as a UTF-8 string, which is equivalent to ASCII for Latin characters.

### Errors

The `DbEnv::set_region_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:

#### EINVAL

If the method was called after DbEnv::open() was called; or if an invalid flag value or parameter was specified.

### Class

DbEnv, DbMpoolFile

### See Also

Memory Pools and Related Methods, DbEnv::get_region_dir()

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