Package org.apache.lucene.backward_codecs.lucene50.compressing

Class Lucene50CompressingStoredFieldsFormat

java.lang.Object

org.apache.lucene.codecs.StoredFieldsFormat

org.apache.lucene.backward_codecs.lucene50.compressing.Lucene50CompressingStoredFieldsFormat

public class Lucene50CompressingStoredFieldsFormat
extends StoredFieldsFormat

A StoredFieldsFormat that compresses documents in chunks in order to improve the compression ratio.

For a chunk size of chunkSize bytes, this StoredFieldsFormat does not support documents larger than (231 - chunkSize) bytes.

For optimal performance, you should use a MergePolicy that returns segments that have the biggest byte size first.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field	Description
protected final int	blockShift	block shift
protected final int	chunkSize	chunk size
protected final CompressionMode	compressionMode	compression mode
protected final String	formatName	format name
protected final int	maxDocsPerChunk	max docs per chunk
protected final String	segmentSuffix	segment suffix

Constructor Summary

Constructors

Constructor	Description
Lucene50CompressingStoredFieldsFormat(String formatName, String segmentSuffix, CompressionMode compressionMode, int chunkSize, int maxDocsPerChunk, int blockShift)	Create a new Lucene50CompressingStoredFieldsFormat.
Lucene50CompressingStoredFieldsFormat(String formatName, CompressionMode compressionMode, int chunkSize, int maxDocsPerChunk, int blockShift)	Create a new Lucene50CompressingStoredFieldsFormat with an empty segment suffix.

Method Summary

Modifier and Type	Method	Description
StoredFieldsReader	fieldsReader(Directory directory, SegmentInfo si, FieldInfos fn, IOContext context)
StoredFieldsWriter	fieldsWriter(Directory directory, SegmentInfo si, IOContext context)
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

formatName

protected final String formatName

format name

segmentSuffix

protected final String segmentSuffix

segment suffix

compressionMode

protected final CompressionMode compressionMode

compression mode

chunkSize

protected final int chunkSize

chunk size

maxDocsPerChunk

protected final int maxDocsPerChunk

max docs per chunk

blockShift

protected final int blockShift

block shift

Constructor Details

Lucene50CompressingStoredFieldsFormat

public Lucene50CompressingStoredFieldsFormat(String formatName,
 CompressionMode compressionMode,
 int chunkSize,
 int maxDocsPerChunk,
 int blockShift)

Create a new Lucene50CompressingStoredFieldsFormat with an empty segment suffix.

See Also:

• Lucene50CompressingStoredFieldsFormat(String, String, CompressionMode, int, int, int)

Lucene50CompressingStoredFieldsFormat

public Lucene50CompressingStoredFieldsFormat(String formatName,
 String segmentSuffix,
 CompressionMode compressionMode,
 int chunkSize,
 int maxDocsPerChunk,
 int blockShift)

Create a new Lucene50CompressingStoredFieldsFormat.

formatName is the name of the format. This name will be used in the file formats to perform codec header checks.

segmentSuffix is the segment suffix. This suffix is added to the result file name only if it's not the empty string.

The compressionMode parameter allows you to choose between compression algorithms that have various compression and decompression speeds so that you can pick the one that best fits your indexing and searching throughput. You should never instantiate two Lucene50CompressingStoredFieldsFormats that have the same name but different CompressionModes.

chunkSize is the minimum byte size of a chunk of documents. A value of 1 can make sense if there is redundancy across fields. maxDocsPerChunk is an upperbound on how many docs may be stored in a single chunk. This is to bound the cpu costs for highly compressible data.

Higher values of chunkSize should improve the compression ratio but will require more memory at indexing time and might make document loading a little slower (depending on the size of your OS cache compared to the size of your index).

Parameters:

formatName - the name of the StoredFieldsFormat

compressionMode - the CompressionMode to use

chunkSize - the minimum number of bytes of a single chunk of stored documents

maxDocsPerChunk - the maximum number of documents in a single chunk

blockShift - the log in base 2 of number of chunks to store in an index block

See Also:

• CompressionMode

Method Details

fieldsReader

public StoredFieldsReader fieldsReader(Directory directory,
 SegmentInfo si,
 FieldInfos fn,
 IOContext context)
                                throws IOException

Specified by:

fieldsReader in class StoredFieldsFormat

Throws:

IOException

fieldsWriter

public StoredFieldsWriter fieldsWriter(Directory directory,
 SegmentInfo si,
 IOContext context)
                                throws IOException

Specified by:

fieldsWriter in class StoredFieldsFormat

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object