it.unimi.di.mg4j.index
Class BitStreamHPIndex

java.lang.Object
  it.unimi.di.mg4j.index.Index
      it.unimi.di.mg4j.index.BitStreamIndex
          it.unimi.di.mg4j.index.BitStreamHPIndex

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

FileHPIndex, InMemoryHPIndex, MemoryMappedHPIndex, RemoteBitStreamHPIndex

public abstract class BitStreamHPIndex
extends BitStreamIndex

A high-performance bitstream-based index.

Implementing subclasses must provide access to the index bitstream (as it happens for a BitStreamIndex) but also to the positions stream, both at byte and bit level.

Wired implementations

The standard readers associated with an instance of this class are of type BitStreamHPIndexReader. Nonetheless, it is possible to generate automatically sources for wired classes that work only for a particular set of codings and flags. The wired classes will be fetched automagically by reflection, if available. Please read the section about performance in the MG4J manual.

Since:

1.1

Author:

Sebastiano Vigna

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.di.mg4j.index.BitStreamIndex

BitStreamIndex.PropertyKeys

Nested classes/interfaces inherited from class it.unimi.di.mg4j.index.Index

Index.EmptyIndexIterator, Index.UriKeys

Field Summary

Fields inherited from class it.unimi.di.mg4j.index.BitStreamIndex

bufferSize, countCoding, DEFAULT_BUFFER_SIZE, DEFAULT_FIXED_QUANTUM, DEFAULT_HEIGHT, DEFAULT_QUANTUM, FIXED_POINT_BITS, FIXED_POINT_MULTIPLIER, frequencyCoding, height, offsets, pointerCoding, positionCoding, quantum, readerConstructor

Fields inherited from class it.unimi.di.mg4j.index.Index

field, hasCounts, hasPayloads, hasPositions, keyIndex, maxCount, numberOfDocuments, numberOfOccurrences, numberOfPostings, numberOfTerms, payload, prefixMap, properties, singletonSet, sizes, termMap, termProcessor

Constructor Summary

BitStreamHPIndex(int numberOfDocuments, int numberOfTerms, long numberOfPostings, long numberOfOccurrences, int maxCount, Payload payload, CompressionFlags.Coding frequencyCoding, CompressionFlags.Coding pointerCoding, CompressionFlags.Coding countCoding, CompressionFlags.Coding positionCoding, int quantum, int height, int bufferSize, TermProcessor termProcessor, String field, Properties properties, StringMap<? extends CharSequence> termMap, PrefixMap<? extends CharSequence> prefixMap, IntList sizes, LongList offsets)

Method Summary

protected Constructor<? extends IndexReader>	getConstructor()
abstract InputBitStream	getPositionsInputBitStream(int bufferSize) Returns an input bit stream over the index.
abstract InputStream	getPositionsInputStream() Returns an input stream over the index.
IndexReader	getReader(int bufferSize) Creates and returns a new IndexReader based on this index.

Methods inherited from class it.unimi.di.mg4j.index.BitStreamIndex

featureName, gaussianGolombModulus, getInputBitStream, getInputStream, golombModulus, quantumSigma, toString

Methods inherited from class it.unimi.di.mg4j.index.Index

documents, documents, documents, getEmptyIndexIterator, getEmptyIndexIterator, getEmptyIndexIterator, getEmptyIndexIterator, getInstance, getInstance, getInstance, getInstance, getInstance, getReader, getTermProcessor, keyIndex

Methods inherited from class java.lang.Object

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

Constructor Detail

BitStreamHPIndex

public BitStreamHPIndex(int numberOfDocuments,
                        int numberOfTerms,
                        long numberOfPostings,
                        long numberOfOccurrences,
                        int maxCount,
                        Payload payload,
                        CompressionFlags.Coding frequencyCoding,
                        CompressionFlags.Coding pointerCoding,
                        CompressionFlags.Coding countCoding,
                        CompressionFlags.Coding positionCoding,
                        int quantum,
                        int height,
                        int bufferSize,
                        TermProcessor termProcessor,
                        String field,
                        Properties properties,
                        StringMap<? extends CharSequence> termMap,
                        PrefixMap<? extends CharSequence> prefixMap,
                        IntList sizes,
                        LongList offsets)

Method Detail

getConstructor

protected Constructor<? extends IndexReader> getConstructor()

Overrides:

getConstructor in class BitStreamIndex

getPositionsInputBitStream

public abstract InputBitStream getPositionsInputBitStream(int bufferSize)
                                                   throws IOException

Returns an input bit stream over the index.

Parameters:

bufferSize - a suggested buffer size.

Returns:

an input bit stream over the index.

Throws:

IOException

getPositionsInputStream

public abstract InputStream getPositionsInputStream()
                                             throws IOException

Returns an input stream over the index.

Returns:

an input stream over the index.

Throws:

IOException

getReader

public IndexReader getReader(int bufferSize)
                      throws IOException

Description copied from class: Index

Creates and returns a new IndexReader based on this index. After that, you can use the reader to read this index.

Overrides:

getReader in class BitStreamIndex

Parameters:

bufferSize - the size of the buffer to be used accessing the reader, or -1 for a default buffer size.

Returns:

a new IndexReader to read this index.

Throws:

IOException