Apache Solr is a very popular open source search platform, based on the Java Lucene Library. Solr is very stable, scalable and reliable and provides a wide set of core search functions. Solr creates an index of the available documents and then you can query Solr to return the most relevant ones for your search.For Drupal users, it is possible to integrate your site with Solr. Index all kinds of content and search through it within a single search page.
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