Class Lucene41StoredFieldsFormat

  extended by org.apache.lucene.codecs.StoredFieldsFormat
      extended by org.apache.lucene.codecs.compressing.CompressingStoredFieldsFormat
          extended by org.apache.lucene.codecs.lucene41.Lucene41StoredFieldsFormat

public final class Lucene41StoredFieldsFormat
extends CompressingStoredFieldsFormat

Lucene 4.1 stored fields format.


This StoredFieldsFormat compresses blocks of 16KB of documents in order to improve the compression ratio compared to document-level compression. It uses the LZ4 compression algorithm, which is fast to compress and very fast to decompress data. Although the compression method that is used focuses more on speed than on compression ratio, it should provide interesting compression ratios for redundant inputs (such as log files, HTML or plain text).

File formats

Stored fields are represented by two files:

  1. A fields data file (extension .fdt). This file stores a compact representation of documents in compressed blocks of 16KB or more. When writing a segment, documents are appended to an in-memory byte[] buffer. When its size reaches 16KB or more, some metadata about the documents is flushed to disk, immediately followed by a compressed representation of the buffer using the LZ4 compression format.

    Here is a more detailed description of the field data file format:


  2. A fields index file (extension .fdx).

Known limitations

This StoredFieldsFormat does not support individual documents larger than (231 - 214) bytes. In case this is a problem, you should use another format, such as Lucene40StoredFieldsFormat.

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

Constructor Summary
          Sole constructor.
Method Summary
Methods inherited from class org.apache.lucene.codecs.compressing.CompressingStoredFieldsFormat
fieldsReader, fieldsWriter, toString
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail


public Lucene41StoredFieldsFormat()
Sole constructor.

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