Lucene 5.1.0 发布，此版本现已提供在：http://www.apache.org/dyn/closer.cgi/lucene/java/5.1.0。

更新内容如下：

• 新特性 (9)

1. LUCENE-6066: Added DiversifiedTopDocsCollector to misc for collecting no more than a given number of results under a choice of key. Introduces new remove method to core's PriorityQueue.
   (Mark Harwood)

2. LUCENE-6191: New spatial 2D heatmap faceting for PrefixTreeStrategy.
   (David Smiley)

3. LUCENE-6227: Added BooleanClause.Occur.FILTER to filter documents without participating in scoring (on the contrary to MUST).
   (Adrien Grand)

4. LUCENE-6294: Added oal.search.CollectorManager to allow for parallelization of the document collection process on IndexSearcher.
   (Adrien Grand)

5. LUCENE-6303: Added filter caching baked into IndexSearcher, disabled by default.
   (Adrien Grand)

6. LUCENE-6304: Added a new MatchNoDocsQuery that matches no documents.
   (Lee Hinman via Adrien Grand)

7. LUCENE-6341: Add a -fast option to CheckIndex.
   (Robert Muir)

8. LUCENE-6355: IndexWriter's infoStream now also logs time to write FieldInfos during merge
   (Lee Hinman via Mike McCandless)

9. LUCENE-6339: Added Near-real time Document Suggester via custom postings format
   (Areek Zillur, Mike McCandless, Simon Willnauer)

• Bug 修复 (10)

1. LUCENE-6368: FST.save can truncate output (BufferedOutputStream may be closed after the underlying stream).
   (Ippei Matsushima via Dawid Weiss)

2. LUCENE-6249: StandardQueryParser doesn't support pure negative clauses.
   (Dawid Weiss)

3. LUCENE-6190: Spatial pointsOnly flag on PrefixTreeStrategy shouldn't switch all predicates to Intersects.
   (David Smiley)

4. LUCENE-6242: Ram usage estimation was incorrect for SparseFixedBitSet when object alignment was different from 8.
   (Uwe Schindler, Adrien Grand)

5. LUCENE-6293: Fixed TimSorter bug.
   (Adrien Grand)

6. LUCENE-6001: DrillSideways hits NullPointerException for certain BooleanQuery searches.
   (Dragan Jotannovic, jane chang via Mike McCandless)

7. LUCENE-6311: Fix NIOFSDirectory and SimpleFSDirectory so that the toString method of IndexInputs confess when they are from a compound file.
   (Robert Muir, Mike McCandless)

8. LUCENE-6381: Add defensive wait time limit in DocumentsWriterStallControl to prevent hangs during indexing if we miss a .notify/All somewhere
   (Mike McCandless)

9. LUCENE-6386: Correct IndexWriter.forceMerge documentation to state that up to 3X (X = current index size) spare disk space may be needed to complete forceMerge(1).
   (Robert Muir, Shai Erera, Mike McCandless)

10. LUCENE-6395: Seeking by term ordinal was failing to set the term's bytes in MemoryIndex
    (Mike McCandless)

• 优化(16)

1. LUCENE-6183, LUCENE-5647: Avoid recompressing stored fields and term vectors when merging segments without deletions. Lucene50Codec's BEST_COMPRESSION mode uses a higher deflate level for more compact storage.
   (Robert Muir)

2. LUCENE-6184: Make BooleanScorer only score windows that contain matches.
   (Adrien Grand)

3. LUCENE-6161: Speed up resolving of deleted terms to docIDs by doing a combined merge sort between deleted terms and segment terms instead of a separate merge sort for each segment.  In delete-heavy use cases this can be a sizable speedup.
   (Mike McCandless)

4. LUCENE-6201: BooleanScorer can now deal with values of minShouldMatch that are greater than one and is used when queries produce dense result sets.
   (Adrien Grand)

5. LUCENE-6218: Don't decode frequencies or match all positions when scoring is not needed.
   (Robert Muir)

6. LUCENE-6233 Speed up CheckIndex when the index has term vectors
   (Robert Muir, Mike McCandless)

7. LUCENE-6198: Added the TwoPhaseIterator API, exposed on scorers which is for now only used on phrase queries and conjunctions in order to check positions lazily if the phrase query is in a conjunction with other queries.
   (Robert Muir, Adrien Grand, David Smiley)

8. LUCENE-6244, LUCENE-6251: All boolean queries but those that have a minShouldMatch > 1 now either propagate or take advantage of the two-phase iteration capabilities added in LUCENE-6198.
   (Adrien Grand, Robert Muir)

9. LUCENE-6241: FSDirectory.listAll() doesnt filter out subdirectories anymore, for faster performance. Subdirectories don't matter to Lucene. If you need to filter out non-index files with some custom usage, you may want to look at the IndexFileNames class.
   (Robert Muir)

10. LUCENE-6262: ConstantScoreQuery does not wrap the inner weight anymore when scores are not required.
    (Adrien Grand)

11. LUCENE-6263: MultiCollector automatically caches scores when several collectors need them.
    (Adrien Grand)

12. LUCENE-6275: SloppyPhraseScorer now uses the same logic as ConjunctionScorer in order to advance doc IDs, which takes advantage of the cost() API.
    (Adrien Grand)

13. LUCENE-6290: QueryWrapperFilter propagates approximations and FilteredQuery rewrites to a BooleanQuery when the filter is a QueryWrapperFilter in order to leverage approximations.
    (Adrien Grand)

14. LUCENE-6318: Reduce RAM usage of FieldInfos when there are many fields.
    (Mike McCandless, Robert Muir)

15. LUCENE-6320: Speed up CheckIndex.
    (Robert Muir)

16. LUCENE-4942: Optimized the encoding of PrefixTreeStrategy indexes for non-point data: 33% smaller index, 68% faster indexing, and 44% faster searching. YMMV
    (David Smiley)

• API 改进 (21)

• > .totalMaxDoc and MergePolicy.OneMerge.totalDocCount ->

1. LUCENE-6204, LUCENE-6208: Simplify CompoundFormat: remove files() and remove files parameter to write().
   (Robert Muir)

2. LUCENE-6217: Add IndexWriter.isOpen and getTragicException.
   (Simon Willnauer, Mike McCandless)

3. LUCENE-6218, LUCENE-6220: Add Collector.needsScores() and needsScores parameter to Query.createWeight().
   (Robert Muir, Adrien Grand)

4. LUCENE-4524, LUCENE-6246, LUCENE-6256, LUCENE-6271: Merge DocsEnum and DocsAndPositionsEnum into a single PostingsEnum iterator.  TermsEnum.docs() and TermsEnum.docsAndPositions() are replaced by TermsEnum.postings().
   (Alan Woodward, Simon Willnauer, Robert Muir, Ryan Ernst)

5. LUCENE-6222: Removed TermFilter, use a QueryWrapperFilter(TermQuery) instead. This will be as efficient now that queries can opt out from scoring.
   (Adrien Grand)

6. LUCENE-6269: Removed BooleanFilter, use a QueryWrapperFilter(BooleanQuery) instead.
   (Adrien Grand)

7. LUCENE-6270: Replaced TermsFilter with TermsQuery, use a QueryWrapperFilter(TermsQuery) instead.
   (Adrien Grand)

8. LUCENE-6223: Move BooleanQuery.BooleanWeight to BooleanWeight.
   (Robert Muir)

9. LUCENE-1518: Make Filter extend Query and return 0 as score.
   (Uwe Schindler, Adrien Grand)

10. LUCENE-6245: Force Filter subclasses to implement toString API from Query.
    (Ryan Ernst)

11. LUCENE-6268: Replace FieldValueFilter and DocValuesRangeFilter with equivalent queries that support approximations.
    (Adrien Grand)

12. LUCENE-6289: Replace DocValuesRangeFilter with DocValuesRangeQuery which supports approximations.
    (Adrien Grand)

13. LUCENE-6266: Remove unnecessary Directory params from SegmentInfo.toString, SegmentInfos.files/toString, and SegmentCommitInfo.toString.
    (Robert Muir)

14. LUCENE-6272: Scorer extends DocSetIdIterator rather than DocsEnum
    (Alan Woodward)

15. LUCENE-6281: Removed support for slow collations from lucene/sandbox. Better performance would be achieved through CollationKeyAnalyzer or ICUCollationKeyAnalyzer.
    (Adrien Grand)

16. LUCENE-6286: Removed IndexSearcher methods that take a Filter object. A BooleanQuery with a filter clause must be used instead.
    (Adrien Grand)

17. LUCENE-6300: PrefixFilter, TermRangeFilter and NumericRangeFilter have been removed. Use PrefixQuery, TermRangeQuery and NumericRangeQuery instead.
    (Adrien Grand)

18. LUCENE-6303: Replaced FilterCache with QueryCache and CachingWrapperFilter with CachingWrapperQuery.
    (Adrien Grand)

19. LUCENE-6317: Deprecate DataOutput.writeStringSet and writeStringStringMap. Use writeSetOfStrings/Maps instead.
    (Mike McCandless, Robert Muir)

20. LUCENE-6307: Rename SegmentInfo.getDocCount -> .maxDoc, SegmentInfos.totalDocCount -> .totalMaxDoc, MergeInfo.totalDocCount.totalMaxDoc
    (Adrien Grand, Robert Muir, Mike McCandless)

21. LUCENE-6367: PrefixQuery now subclasses AutomatonQuery, removing the specialized PrefixTermsEnum.
    (Robert Muir, Mike McCandless)

• 其他 (6)

1. LUCENE-6248: Remove unused odd constants from StandardSyntaxParser.jj
   (Dawid Weiss)

2. LUCENE-6193: Collapse identical catch branches in try-catch statements.
   (shalin)

3. LUCENE-6239: Removed RAMUsageEstimator's sun.misc.Unsafe calls.
   (Robert Muir, Dawid Weiss, Uwe Schindler)

4. LUCENE-6292: Seed StringHelper better.
   (Robert Muir)

5. LUCENE-6333: Refactored queries to delegate their equals and hashcode impls to the super class.
   (Lee Hinman via Adrien Grand)

6. LUCENE-6343: DefaultSimilarity javadocs had the wrong float value to demonstrate precision of encoded norms
   (András Péteri via Mike McCandless)

更多详细内容请看更新日志。

Lucene 是apache软件基金会一个开放源代码的全文检索引擎工具包，是一个全文检索引擎的架构，提供了完整的查询引擎和索引引擎，部分文本分析引擎。 Lucene的目的是为软件开发人员提供一个简单易用的工具包，以方便的在目标系统中实现全文检索的功能，或者是以此为基础建立起完整的全文检索引擎。

Lucene 最初是由Doug Cutting所撰写的，是一位资深全文索引/检索专家，曾经是V-Twin搜索引擎的主要开发者，后来在Excite担任高级系统架构设计师，目前从事 于一些INTERNET底层架构的研究。他贡献出Lucene的目标是为各种中小型应用程式加入全文检索功能。

OSChina 使用 Lucene 实现全文搜索。

在线Javadoc：http://tool.oschina.net/apidocs/apidoc?api=lucene-3.6.0