Berkeley DB

Db.set_h_hash

						import com.sleepycat.db.*;
						public interface DbHash
						{
						public abstract int hash(Db db, byte[] data, int len);
						}
						public class Db
						{
						public void set_h_hash(DbHash h_hash)
						throws DbException;
						...
						}
					

Description

Set a user-defined hash method; if no hash method is specified, a default hash method is used. Because no hash method performs equally well on all possible data, the user may find that the built-in hash method performs poorly with a particular data set. User-specified hash functions must take a pointer to a byte string and a length as arguments, and return a value of type int. The hash function must handle any key values used by the application (possibly including zero-length keys).

If a hash method is specified, Db.open will ...