Apache Solr 7.4.0 发布了，Solr 是来自 Apache Lucene 项目的流行的、快速的、开源的 NoSQL 搜索平台。Solr 使用 Java 语言开发，主要基于 HTTP 和 Apache Lucene 实现，其主要功能包括强大的全文搜索、命中突出显示、丰富的文档分析、地理空间搜索、广泛的 REST API 以及并行 SQL。
此次更新主要内容包括：
A new 'relatedness()' aggregate function for JSON Faceting to enable building Semantic Knowledge Graphs.
Added the TaggerRequestHandler (AKA SolrTextTagger) for tagging text. It's used as a component of NER/ERD systems including query-understanding.
The "Auto Scaling" feature area has been added to and enhanced a lot.
The "Streaming Expressions" feature area has been added to and enhanced a lot.
Upgraded from Log4j 1.x to 2.x. Solr continues to log via SLF4J.
详情见发布公告。