Package org.apache.lucene.codecs.compressing

Class CompressingStoredFieldsFormat

java.lang.Object

org.apache.lucene.codecs.StoredFieldsFormat

org.apache.lucene.codecs.compressing.CompressingStoredFieldsFormat

Direct Known Subclasses:

Lucene41StoredFieldsFormat

public class CompressingStoredFieldsFormat
extends StoredFieldsFormat

A StoredFieldsFormat that is very similar to Lucene40StoredFieldsFormat but 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. In case this is a problem, you should use another format, such as Lucene40StoredFieldsFormat.

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

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
StoredFieldsReader	fieldsReader(Directory directory, SegmentInfo si, FieldInfos fn, IOContext context)	Returns a StoredFieldsReader to load stored fields.
StoredFieldsWriter	fieldsWriter(Directory directory, SegmentInfo si, IOContext context)	Returns a StoredFieldsWriter to write stored fields.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

CompressingStoredFieldsFormat

public CompressingStoredFieldsFormat(String formatName,
                                     CompressionMode compressionMode,
                                     int chunkSize)

Create a new CompressingStoredFieldsFormat with an empty segment suffix.

See Also:

CompressingStoredFieldsFormat(String, String, CompressionMode, int)

CompressingStoredFieldsFormat

public CompressingStoredFieldsFormat(String formatName,
                                     String segmentSuffix,
                                     CompressionMode compressionMode,
                                     int chunkSize)

Create a new CompressingStoredFieldsFormat.

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 CompressingStoredFieldsFormats 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. In that case, both performance and compression ratio should be better than with Lucene40StoredFieldsFormat with compressed fields.

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

See Also:

CompressionMode

Method Detail

fieldsReader

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

Description copied from class: StoredFieldsFormat

Returns a StoredFieldsReader to load stored fields.

Specified by:

fieldsReader in class StoredFieldsFormat

Throws:

IOException

fieldsWriter

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

Description copied from class: StoredFieldsFormat

Returns a StoredFieldsWriter to write stored fields.

Specified by:

fieldsWriter in class StoredFieldsFormat

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object