com.sleepycat.db

Interface SecondaryKeyCreator

All Known Implementing Classes:

SerialSerialKeyCreator, TupleSerialKeyCreator, TupleSerialMarshalledKeyCreator, TupleTupleKeyCreator, TupleTupleMarshalledKeyCreator

public interface SecondaryKeyCreator

The interface implemented for extracting single-valued secondary keys from primary records.

The key creator object is specified by calling SecondaryConfig.setKeyCreator. The secondary database configuration is specified when calling Environment.openSecondaryDatabase.

For example:

    class MyKeyCreator implements SecondaryKeyCreator {
        public boolean createSecondaryKey(SecondaryDatabase secondary,
                                            DatabaseEntry key,
                                            DatabaseEntry data,
                                            DatabaseEntry result)
            throws DatabaseException {
            //
            // DO HERE: Extract the secondary key from the primary key and
            // data, and set the secondary key into the result parameter.
            //
            return true;
        }
    }
    ...
    SecondaryConfig secConfig = new SecondaryConfig();
    secConfig.setKeyCreator(new MyKeyCreator());
    // Now pass secConfig to Environment.openSecondaryDatabase

Method Summary

Modifier and Type	Method and Description
boolean	createSecondaryKey(SecondaryDatabase secondary, DatabaseEntry key, DatabaseEntry data, DatabaseEntry result) Creates a secondary key entry, given a primary key and data entry.

Method Detail

createSecondaryKey

boolean createSecondaryKey(SecondaryDatabase secondary,
                           DatabaseEntry key,
                           DatabaseEntry data,
                           DatabaseEntry result)
                    throws DatabaseException

Creates a secondary key entry, given a primary key and data entry.

A secondary key may be derived from the primary key, primary data, or a combination of the primary key and data. For secondary keys that are optional, the key creator method may return false and the key/data pair will not be indexed. To ensure the integrity of a secondary database the key creator method must always return the same result for a given set of input parameters.

Parameters:

secondary - the database to which the secondary key will be added. This parameter is passed for informational purposes but is not commonly used.

key - the primary key entry. This parameter must not be modified by this method.

data - the primary data entry. This parameter must not be modified by this method.

result - the secondary key created by this method.

Returns:

true if a key was created, or false to indicate that the key is not present.

Throws:

DatabaseException - if an error occurs attempting to create the secondary key.