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 `Lucene50CompressingStoredFieldsFormat`s that have the same name but different `CompressionMode`s.

`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`