it.unimi.di.mg4j.index
Class AbstractBitStreamIndexWriter

java.lang.Object
  it.unimi.di.mg4j.index.AbstractBitStreamIndexWriter

All Implemented Interfaces:

IndexWriter

Direct Known Subclasses:

BitStreamHPIndexWriter, BitStreamIndexWriter

public abstract class AbstractBitStreamIndexWriter
extends Object
implements IndexWriter

An abstract bitstream-based index writer, providing common variables and a basic printStats(PrintStream) implementation.

Compression flags

Implementing subclasses need to know the compression method that they should use to write frequencies, pointers, payloads, counts and positions (and whether to write any of them). This information is passed to the constructor using a suitable flag map (see CompressionFlags).

Since:

1.2

Author:

Sebastiano Vigna

Field Summary

long	bitsForCounts The number of bits written for counts.
long	bitsForFrequencies The number of bits written for frequencies.
long	bitsForPayloads The number of bits written for payloads.
long	bitsForPointers The number of bits written for document pointers.
long	bitsForPositions The number of bits written for positions.
protected CompressionFlags.Coding	countCoding The coding for counts.
protected int	currentTerm The current term.
Map<CompressionFlags.Component,CompressionFlags.Coding>	flags The flag map.
protected CompressionFlags.Coding	frequencyCoding The coding for frequencies.
protected boolean	hasCounts Whether this index contains counts.
protected boolean	hasPayloads Whether this index contains payloads.
protected boolean	hasPositions Whether this index contains positions.
protected int	numberOfDocuments The number of documents of the collection to be indexed.
protected long	numberOfOccurrences The number of indexed occurrences.
protected long	numberOfPostings The number of indexed postings (pairs term/document).
protected CompressionFlags.Coding	pointerCoding The coding for pointers.
protected CompressionFlags.Coding	positionCoding The coding for positions.

Constructor Summary

AbstractBitStreamIndexWriter(int numberOfDocuments, Map<CompressionFlags.Component,CompressionFlags.Coding> flags)

Method Summary

void	printStats(PrintStream stats) Writes to the given print stream statistical information about the index just built.

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.di.mg4j.index.IndexWriter

close, newDocumentRecord, newInvertedList, properties, writeDocumentPointer, writeDocumentPositions, writeFrequency, writePayload, writePositionCount, writtenBits

Field Detail

numberOfDocuments

protected final int numberOfDocuments

The number of documents of the collection to be indexed.

flags

public Map<CompressionFlags.Component,CompressionFlags.Coding> flags

The flag map.

frequencyCoding

protected CompressionFlags.Coding frequencyCoding

The coding for frequencies.

pointerCoding

protected CompressionFlags.Coding pointerCoding

The coding for pointers.

countCoding

protected CompressionFlags.Coding countCoding

The coding for counts.

positionCoding

protected CompressionFlags.Coding positionCoding

The coding for positions.

hasPayloads

protected final boolean hasPayloads

Whether this index contains payloads.

hasCounts

protected final boolean hasCounts

Whether this index contains counts.

hasPositions

protected final boolean hasPositions

Whether this index contains positions.

numberOfPostings

protected long numberOfPostings

The number of indexed postings (pairs term/document).

numberOfOccurrences

protected long numberOfOccurrences

The number of indexed occurrences.

currentTerm

protected int currentTerm

The current term.

bitsForFrequencies

public long bitsForFrequencies

The number of bits written for frequencies.

bitsForPointers

public long bitsForPointers

The number of bits written for document pointers.

bitsForCounts

public long bitsForCounts

The number of bits written for counts.

bitsForPayloads

public long bitsForPayloads

The number of bits written for payloads.

bitsForPositions

public long bitsForPositions

The number of bits written for positions.

Constructor Detail

AbstractBitStreamIndexWriter

public AbstractBitStreamIndexWriter(int numberOfDocuments,
                                    Map<CompressionFlags.Component,CompressionFlags.Coding> flags)

Method Detail

printStats

public void printStats(PrintStream stats)

Description copied from interface: IndexWriter

Writes to the given print stream statistical information about the index just built. This method must be called after IndexWriter.close().

Specified by:

printStats in interface IndexWriter

Parameters:

stats - a print stream where statistical information will be written.