Class CompressingStoredFieldsFormat

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.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk
Inheritance
System.Object
StoredFieldsFormat
CompressingStoredFieldsFormat
Lucene41StoredFieldsFormat
Namespace: Lucene.Net.Codecs.Compressing
Assembly: Lucene.Net.dll
Syntax
public class CompressingStoredFieldsFormat : StoredFieldsFormat

Constructors

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CompressingStoredFieldsFormat(String, CompressionMode, Int32)

Create a new CompressingStoredFieldsFormat with an empty segment suffix.

Declaration
public CompressingStoredFieldsFormat(string formatName, CompressionMode compressionMode, int chunkSize)
Parameters
Type Name Description
System.String formatName
CompressionMode compressionMode
System.Int32 chunkSize
See Also
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CompressingStoredFieldsFormat(String, String, CompressionMode, Int32)

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 (CheckHeader(DataInput, String, Int32, Int32)).

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 Lucene.Net.Codecs.Compressing.CompressingStoredFieldsFormat.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).

Declaration
public CompressingStoredFieldsFormat(string formatName, string segmentSuffix, CompressionMode compressionMode, int chunkSize)
Parameters
Type Name Description
System.String formatName

The name of the StoredFieldsFormat.

System.String segmentSuffix
CompressionMode compressionMode

The CompressionMode to use.

System.Int32 chunkSize

The minimum number of bytes of a single chunk of stored documents.

See Also

Methods

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FieldsReader(Directory, SegmentInfo, FieldInfos, IOContext)

Declaration
public override StoredFieldsReader FieldsReader(Directory directory, SegmentInfo si, FieldInfos fn, IOContext context)
Parameters
Type Name Description
Directory directory
SegmentInfo si
FieldInfos fn
IOContext context
Returns
Type Description
StoredFieldsReader
Overrides
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FieldsWriter(Directory, SegmentInfo, IOContext)

Declaration
public override StoredFieldsWriter FieldsWriter(Directory directory, SegmentInfo si, IOContext context)
Parameters
Type Name Description
Directory directory
SegmentInfo si
IOContext context
Returns
Type Description
StoredFieldsWriter
Overrides
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ToString()

Declaration
public override string ToString()
Returns
Type Description
System.String