#include <db.h>

int
DB->set_h_ffactor(DB *db, u_int32_t h_ffactor);  

Set the desired density within the hash table. If no value is specified, the fill factor will be selected dynamically as pages are filled.

The density is an approximation of the number of keys allowed to accumulate in any one bucket, determining when the hash table grows or shrinks. If you know the average sizes of the keys and data in your data set, setting the fill factor can enhance performance. A reasonable rule computing fill factor is to set it to the following:

             (pagesize - 32) / (average_key_size + average_data_size + 8) 

The DB->set_h_ffactor() method configures a database, not only operations performed using the specified DB handle.

The DB->set_h_ffactor() method may not be called after the DB->open() method is called. If the database already exists when DB->open() is called, the information specified to DB->set_h_ffactor() will be ignored.

The DB->set_h_ffactor() method returns a non-zero error value on failure and 0 on success.