com.bigdata.striterator

Class DistinctFilter<E>

java.lang.Object

com.bigdata.striterator.DistinctFilter<E>

All Implemented Interfaces:

IChunkConverter<E,E>

Deprecated.

by JVMDistinctBindingSetsOp

public abstract class DistinctFilter<E>
extends Object
implements IChunkConverter<E,E>

A filter that imposes a DISTINCT constraint on the ISolutions generated by an IRule. The filter is optimized if only a single chunk is visited by the source iterator. Otherwise, the filter is implemented using a BTree backed by a TemporaryStore.

When more than one chunk is processed, ISolutions are transformed into unsigned byte[] keys. The BTree is tested for each such key. If the key is NOT found, then it is inserted into the BTree and the solution is passed by the filter. Otherwise the solution is rejected by the filter. The backing BTree is closed when the filter is finalized, but it will hold a hard reference to the TemporaryStore until then. Solutions are processed in chunks for efficient ordered reads and writes on the BTree.

Version:

$Id$

Author:

Bryan Thompson

Constructor Summary

Constructors

Constructor and Description
DistinctFilter(IIndexManager indexManager) Deprecated.

Method Summary

Methods

Modifier and Type	Method and Description
E[]	convert(IChunkedOrderedIterator<E> src) Deprecated. Convert the next chunk of element(s) from the source iterator into target element(s).
protected abstract byte[]	getSortKey(E e) Deprecated. Return an unsigned byte[] key that is a representation of the visited element.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DistinctFilter

public DistinctFilter(IIndexManager indexManager)

Deprecated.

Parameters:

indexManager - Used to lazily obtain a TemporaryStore.

Method Detail

convert

public E[] convert(IChunkedOrderedIterator<E> src)

Deprecated.

Description copied from interface: IChunkConverter

Convert the next chunk of element(s) from the source iterator into target element(s).

Note: This method will only be invoked if ChunkedConvertingIterator.hasNext() reports true for the source iterator.

Note: Iterators are single-threaded so the implementation of this method does not need to be thread-safe.

Specified by:

convert in interface IChunkConverter<E,E>

Parameters:

src - The source iterator.

Returns:

The target chunk (not null, but may be empty).

getSortKey

protected abstract byte[] getSortKey(E e)

Deprecated.

Return an unsigned byte[] key that is a representation of the visited element. Elements are judged for distinctness in terms of the generated sort key.

Parameters:

e - The visited element.

Returns:

The unsigned byte[] key.