Apache Solr 5.5.0 发布，Solr是一个高性能，采用Java开发，基于Lucene的全文搜索服务器。文档通过Http利用XML加到一个搜索集合中。查询该集合也是通过 http收到一个XML/JSON响应来实现。它的主要特性包括：高效、灵活的缓存功能，垂直搜索功能，高亮显示搜索结果，通过索引复制来提高可用性，提 供一套强大Data Schema来定义字段，类型和设置文本分析，提供基于Web的管理界面等。 该版本值得关注的改进内容包括： * The schema version has been increased to 1.6, and Solr now returns
non-stored doc values fields along with stored fields
* The PERSIST CoreAdmin action has been removed
* The <mergePolicy> element is deprecated in favor of a similar
<mergePolicyFactory> element, in solrconfig.xml
* CheckIndex now works on HdfsDirectory
* RuleBasedAuthorizationPlugin now allows wildcards in the role, and
accepts an 'all' permission
* Users can now choose compression mode in SchemaCodecFactory
* Solr now supports Lucene's XMLQueryParser
* Collections APIs now have async support
* Uninverted field faceting is re-enabled, for higher performance on
rarely changing indices 完整的改进记录请看：https://lucene.apache.org/solr/5_5_0/changes/Changes.htm | 
