com.sleepycat.je
Interface SecondaryKeyCreator

All Known Implementing Classes:

SerialSerialKeyCreator, TupleSerialKeyCreator, TupleTupleKeyCreator

public interface SecondaryKeyCreator

Implemented to create secondary keys for a SecondaryDatabase.

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.

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());
   

Method Summary

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

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

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

Parameters:

secondary - the database to which the secondary key will be added.

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.