#include <db.h>

int
DB_ENV->set_ext_file_threshold(DB_ENV *dbenv, u_int32_t bytes, 
                           u_int32_t flags);  

The DB_ENV->set_ext_file_threshold() method sets a default size for the environment which is used to determine when a data item will be stored as an external file. Data items sized less than this threshold are stored as normal data within the database. Data items larger than this size are stored on-disk in a subdirectory set aside for the purpose.

If this threshold value is set to 0, then external file support is turned off by default for databases created in the environment. If this method is never called, then the default external file threshold is 0.

This method only sets the default external file threshold for the environment. The external file threshold can be set for individual databases created within the environment using DB->set_ext_file_threshold() .

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

You may call this method at any time after the DB_ENV handle has been created.

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