Db::set_h_ffactor()
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## Db::set_h_ffactor()

    #include <db_cxx.h>

    int
    Db::set_h_ffactor(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 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

#### h_ffactor

The h_ffactor parameter is the desired density within the hash table.

### Errors

The `Db::set_h_ffactor()` 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 Db::open() was called; or if an invalid flag value or parameter was specified.

### Class

Db

### See Also

Database and Related Methods

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