com.sleepycat.bind.tuple
Class TupleTupleKeyCreator<E>

java.lang.Object
  com.sleepycat.bind.tuple.TupleBase<E>
      com.sleepycat.bind.tuple.TupleTupleKeyCreator<E>

All Implemented Interfaces:

ForeignKeyNullifier, SecondaryKeyCreator

Direct Known Subclasses:

TupleTupleMarshalledKeyCreator

public abstract class TupleTupleKeyCreator<E>
extends TupleBase<E>
implements SecondaryKeyCreator, ForeignKeyNullifier

An abstract key creator that uses a tuple key and a tuple data entry. This class takes care of converting the key and data entry to/from TupleInput and TupleOutput objects. The following abstract method must be implemented by a concrete subclass to create the index key using these objects

• createSecondaryKey(TupleInput,TupleInput,TupleOutput)

If ForeignKeyDeleteAction.NULLIFY was specified when opening the secondary database, the following method must be overridden to nullify the foreign index key. If NULLIFY was not specified, this method need not be overridden.

• nullifyForeignKey(TupleInput,TupleOutput)

If ForeignKeyDeleteAction.NULLIFY was specified when creating the secondary, this method is called when the entity for this foreign key is deleted. If NULLIFY was not specified, this method will not be called and may always return false.

TupleTupleKeyCreator

public TupleTupleKeyCreator()

Creates a tuple-tuple key creator.

createSecondaryKey

public boolean createSecondaryKey(SecondaryDatabase db,
                                  DatabaseEntry primaryKeyEntry,
                                  DatabaseEntry dataEntry,
                                  DatabaseEntry indexKeyEntry)

Description copied from interface: SecondaryKeyCreator

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.

Specified by:

createSecondaryKey in interface SecondaryKeyCreator

Parameters:

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

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

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

indexKeyEntry - the secondary key created by this method.

Returns:

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

nullifyForeignKey

public boolean nullifyForeignKey(SecondaryDatabase db,
                                 DatabaseEntry dataEntry)

Description copied from interface: ForeignKeyNullifier

Sets the foreign key reference to null in the datum of the primary database.

Specified by:

nullifyForeignKey in interface ForeignKeyNullifier

Parameters:

db - the database in which the foreign key integrity constraint is defined. This parameter is passed for informational purposes but is not commonly used.

dataEntry - the existing primary datum in which the foreign key reference should be set to null. This parameter should be updated by this method if it returns true.

Returns:

true if the datum was modified, or false to indicate that the key is not present.

createSecondaryKey

public abstract boolean createSecondaryKey(TupleInput primaryKeyInput,
                                           TupleInput dataInput,
                                           TupleOutput indexKeyOutput)

Creates the index key from primary key tuple and data tuple.

Parameters:

primaryKeyInput - is the TupleInput for the primary key entry.

dataInput - is the TupleInput for the data entry.

indexKeyOutput - is the destination index key tuple.

Returns:

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

nullifyForeignKey

public boolean nullifyForeignKey(TupleInput dataInput,
                                 TupleOutput dataOutput)

Clears the index key in the tuple data entry. The dataInput should be read and then written to the dataOutput, clearing the index key in the process.

The secondary key should be output or removed by this method such that createSecondaryKey(com.sleepycat.db.SecondaryDatabase, com.sleepycat.db.DatabaseEntry, com.sleepycat.db.DatabaseEntry, com.sleepycat.db.DatabaseEntry) will return false. Other fields in the data object should remain unchanged.

Parameters:

dataInput - is the TupleInput for the data entry.

dataOutput - is the destination TupleOutput.

Returns:

true if the key was cleared, or false to indicate that the key is not present and no change is necessary.