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From Mark Miller <>
Subject Lucene 2.9 RC5 now available for testing
Date Sat, 19 Sep 2009 16:59:13 GMT
Hash: SHA1

Hello Lucene users,

On behalf of the Lucene dev community (a growing community far larger
than just the committers) I would like to announce the fifth (and
hopefully last) release candidate for Lucene 2.9.

Please download and check it out - take it for a spin and kick the
tires. If all goes well, we hope to release the final version of
Lucene 2.9 very shortly.

The following issues were addressed since the last release candidate:
LUCENE-1919 - Fix analysis back compat break.
LUCENE-1918 - fix corner cases (resulting in exceptions) when passing
ParallelReader to IndexWriter.addIndexes
LUCENE-1913 - FastVectorHighlighter: AIOOBE occurs if one PhraseQuery
is contained by another PhraseQuery
LUCENE-1911 - Add a new DocIdSet.isCacheable() method that defaults to
false, but is true for some DocIdSet impls, that are effective and use
no disk I/O during iteration (OpenBitSet, SortedVIntList, DocIdBitSet,
EMPTY_DOCIDSET, some FieldCache filter impls). CachingWrapperFilter
now copies all DocIdSets, which are not cacheable, into an
OpenBitSetDISI for caching.
LUCENE-1912 - fix issue when 2 or more terms are concatenated in
LUCENE-1908 - Scoring documentation imrovements in Similarity javadocs.
LUCENE-1872 - Javadocs updates of Numeric*

While we generally try and maintain full backwards compatibility
between major versions, Lucene 2.9 has a variety of breaks that are
spelled out in the 'Changes in backwards compatibility policy' section
of CHANGES.txt.

We recommend that you recompile your application with Lucene 2.9
rather than attempting to “drop” it in. This will alert you to any
issues you may have to fix if you are affected by one of the backward
compatibility breaks. As always, its a really good idea to thoroughly
read CHANGES.txt before upgrading. Also, remember that this is a
release candidate, and not the final Lucene 2.9 release.

Lucene 2.9 comes with a bevy of new features, including:

  * Per segment searching and caching (can lead to much faster reopen
    among other things)

  * Near real-time search capabilities added to IndexWriter

  * New Query types

  * Smarter, more scalable multi-term queries (wildcard, range, etc)

  * A freshly optimized Collector/Scorer API

  * Improved Unicode support and the addition of Collation contrib

  * A new Attribute based TokenStream API

  * A new QueryParser framework in contrib with a core QueryParser
    replacement impl included.

  * Scoring is now optional when sorting by Field, or using a custom
    Collector, gaining sizable performance when scores are not

  * New analyzers (PersianAnalyzer, ArabicAnalyzer,

  * New fast-vector-highlighter

  * Lucene now includes high-performance handling of numeric fields.
    Such fields are indexed with a trie structure, enabling simple to
    use and much faster numeric range searching without having to
    externally pre-process numeric values into textual values.


And many, many more features, bug fixes, optimizations, and various
improvements. You can find the full list of changes here:

HTML version:

Text version:

Many changes have also occurred in Lucene's Contrib area:

HTML version:

Text version:

Download release candidate 5 here:

Be sure to report back with any issues you find!


Mark Miller
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Mozilla -


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