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font-size: xx-small">TM</span></div> </div> <div id="search" style="float:right;zoom:1"> <form id="quick-search" method="GET" action="https://web.archive.org/web/20210123092442/https://sematext.com/opensee/lucene" name="searchform"> <fieldset> <input type="search" id="q" name="q" placeholder="Search with Apache Solr..." class="class1 class2 hint" accesskey="q"> </fieldset> </form> </div> <div id="nav"> <ul> <li><a href="/web/20210123092442/https://lucene.apache.org/core/index.html">Core</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/corenews.html">News</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/downloads.html">Download</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/discussion.html">Mailing Lists</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/documentation.html">Documentation</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/quickstart.html">Tutorials</a></li> <li><a href="https://web.archive.org/web/20210123092442/https://issues.apache.org/jira/browse/LUCENE">Issue Tracker</a></li> <li><a class="last" href="/web/20210123092442/https://lucene.apache.org/">Lucene TLP</a></li> </ul> </div> <div id="slides"> <div class="slideshow" id="mantleSlides"> <div id="slide1"> <div class="callout"> Ultra-fast Search Library<br/> </div> <div class="descwrapper"> <div class="description"> Apache Lucene sets the standard for search and indexing performance </div> </div> <div class="mantle"> <img alt="Apache Lucene" src="/web/20210123092442im_/https://lucene.apache.org/theme/images/lucene/core/mantle-lucene.png"/> </div> </div> <div id="slide2" style="display:none"> <div class="callout"> Proven search capabilities<br/> </div> <div class="descwrapper"> <div class="description"> Lucene is the de facto standard for search libraries </div> </div> <div class="mantle"> <img alt="Lucene Power" src="/web/20210123092442im_/https://lucene.apache.org/theme/images/lucene/mantle-power.png"/> </div> </div> <div id="slide3" style="display:none"> <div class="callout"> Innovation and Maturity </div> <div class="descwrapper"> <div class="description"> Lucene has proven stability as well as a track record of innovation </div> </div> <div class="mantle"> <img alt="Apache Lucene" src="/web/20210123092442im_/https://lucene.apache.org/theme/images/lucene/core/mantle-innovation.png"/> </div> </div> <div id="slide4" style="display:none"> <div class="callout"> Apache 2.0 licensed </div> <div class="descwrapper"> <div class="description"> Apache Lucene is distributed under a commercially friendly Apache Software license </div> </div> <div class="mantle"> <img alt="Apache Software Foundation" src="/web/20210123092442im_/https://lucene.apache.org/theme/images/lucene/mantle-asf.png"/> </div> </div> </div> <div class="controls"> <a class="next" id="next" title="Next" href="#">Next</a> <a class="previous" id="previous" title="Previous" href="#">Previous</a> <a class="start" id="start" title="Start" href="#" style="display: none; ">Start</a> <a class="stop" id="stop" title="Stop" href="#">Stop</a> </div> <script type="text/javascript"> function StartSlides() { new Slides('mantleSlides'); } document.observe('dom:loaded', StartSlides); </script> </div>  </div>  <div id="content-wrap" class="clearfix"> <div id="main"> <div> <h1 class="title">Apache Lucene Core</h1> <p>Apache Lucene<span style="vertical-align: super; font-size: xx-small">TM</span> is a high-performance, full-featured text search engine library written entirely in Java. It is a technology suitable for nearly any application that requires full-text search, especially cross-platform.</p> <p>Apache Lucene is an open source project available for free download. Please use the links on the right to access Lucene.</p> <h1 id="lucenetm-features">Lucene<span style="vertical-align: super; font-size: xx-small">TM</span> Features</h1> <p>Lucene offers powerful features through a simple API:</p> <h2 id="scalable-high-performance-indexing">Scalable, High-Performance Indexing</h2> <ul> <li>over <a href="https://web.archive.org/web/20210123092442/http://home.apache.org/~mikemccand/lucenebench/indexing.html">150GB/hour on modern hardware</a></li> <li>small RAM requirements -- only 1MB heap</li> <li>incremental indexing as fast as batch indexing</li> <li>index size roughly 20-30% the size of text indexed</li> </ul> <h2 id="powerful-accurate-and-efficient-search-algorithms">Powerful, Accurate and Efficient Search Algorithms</h2> <ul> <li>ranked searching -- best results returned first</li> <li>many powerful query types: phrase queries, wildcard queries, proximity queries, range queries and more</li> <li>fielded searching (e.g. title, author, contents)</li> <li>sorting by any field</li> <li>multiple-index searching with merged results</li> <li>allows simultaneous update and searching</li> <li>flexible faceting, highlighting, joins and result grouping</li> <li>fast, memory-efficient and typo-tolerant suggesters</li> <li>pluggable ranking models, including the <a href="https://web.archive.org/web/20210123092442/http://en.wikipedia.org/wiki/Vector_Space_Model">Vector Space Model</a> and <a href="https://web.archive.org/web/20210123092442/http://en.wikipedia.org/wiki/Okapi_BM25">Okapi BM25</a></li> <li>configurable storage engine (codecs)</li> </ul> <h2 id="cross-platform-solution">Cross-Platform Solution</h2> <ul> <li>Available as Open Source software under the <a href="https://web.archive.org/web/20210123092442/https://www.apache.org/licenses/LICENSE-2.0.html">Apache License</a> which lets you use Lucene in both commercial and Open Source programs</li> <li>100%-pure Java</li> <li>Implementations <a href="https://web.archive.org/web/20210123092442/https://cwiki.apache.org/confluence/display/lucene/LuceneImplementations">in other programming languages available</a> that are index-compatible</li> </ul> </div> </div> <div id="sidebar"> <div class="button-wrapper"> <div class="button-green"> <a href="/web/20210123092442/https://lucene.apache.org/core/downloads.html">Download</a> <div class="flap top">Click to</div> <div class="flap bottom">Apache Lucene 8.7.0</div> </div> <div class="download-desc">Apache Lucene 8.7.0</div> </div> <h1 id="resources">Resources</h1> <ul> <li><a href="/web/20210123092442/https://lucene.apache.org/core/discussion.html">Mailing Lists</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/developer.html">Developer</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/features.html">Features</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/downloads.html">Releases</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/core/systemreqs.html">System Requirements</a></li> </ul> <h1 id="release-docs">Release Docs</h1> <ul> <li><a href="/web/20210123092442/https://lucene.apache.org/core/8_7_0/index.html">8.7.0</a></li> </ul> <h1 id="about">About</h1> <ul> <li><a href="https://web.archive.org/web/20210123092442/https://www.apache.org/licenses/">License</a></li> <li><a href="/web/20210123092442/https://lucene.apache.org/whoweare.html">Who We are</a></li> </ul> <h1 id="events">Events</h1> <ul> <li><a href="https://web.archive.org/web/20210123092442/https://www.apache.org/events/current-event.html" target="_blank"><img src="https://web.archive.org/web/20210123092442im_/https://www.apache.org/events/current-event-125x125.png"></a></li> </ul> <h1 id="asf-links">ASF links</h1> <ul> <li><a href="https://web.archive.org/web/20210123092442/https://www.apache.org/">Apache Software Foundation</a></li> <li><a href="https://web.archive.org/web/20210123092442/https://www.apache.org/foundation/thanks.html">Thanks</a></li> <li><a href="https://web.archive.org/web/20210123092442/https://www.apache.org/foundation/sponsorship.html">Become a Sponsor</a></li> <li><a href="https://web.archive.org/web/20210123092442/https://www.apache.org/security/">Security</a></li> </ul> <h1 id="related-projects">Related Projects</h1> <ul> <li><a href="https://web.archive.org/web/20210123092442/http://hadoop.apache.org/">Apache Hadoop</a></li> <li><a href="https://web.archive.org/web/20210123092442/http://manifoldcf.apache.org/">Apache ManifoldCF</a></li> <li><a href="https://web.archive.org/web/20210123092442/http://lucenenet.apache.org/">Apache Lucene.Net</a></li> <li><a href="https://web.archive.org/web/20210123092442/http://mahout.apache.org/">Apache Mahout</a></li> <li><a href="https://web.archive.org/web/20210123092442/http://nutch.apache.org/">Apache Nutch</a></li> <li><a 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