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From Michael McCandless <>
Subject draft 2.4 announcement
Date Mon, 29 Sep 2008 19:00:17 GMT

Here's my current draft -- any feedback?

Release 2.4.0 of Lucene is now available!

Many new features, fixes and optimizations have happened since 2.4,

   * New IndexWriter constructors now default autoCommit to false.

   * New commit() method in IndexWriter, lets you control when changes
     are made visible & permanent in the index.

   * A machine or OS crash, or power loss, while IndexWriter is writing
     to an index should no longer corrupt the index (LUCENE-1044).

   * TimeLimitedCollector adds timeout to searches

   * Delete documents by Query in IndexWriter

   * Pure boolean indexing (no frequency, positions nor payloads are
     indexed) using Field.setOmitTf()

   * A new Directory implementation, NIOFSDirectory, using java.nio's
     APIs to allow multiple threads to read from the same open file
     without locking.

   * IndexWriter.expungeDeletes() reclaims disk space from deleted
     documents by merging away segments that have deletions.

   * All filters now return a DocIdSet instead of java.util.BitSet,
     making filters more efficient and flexible.

   * IndexReader can be opened with new readOnly=true mode, which gives
     better performance in a multi-threaded environment.

The detailed changes are here:

   <URL to 2.4 Changes.html>

Lucene 2.4 includes index format changes that are not readable by older
versions of Lucene.  Lucene 2.4 can both read and update older Lucene
indexes.  Adding to an index with an older format will cause it to be
converted to the newer format.

Binary and source distributions are available at

Lucene artifacts are also available in the Maven2 repository at


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