The two top Hadoop distributions (Cloudera and Hortonworks but remember that Hadoop is a Free Software and many companies do not pay anything for using it!) include Apache Solr as Hadoop search tool See apache-solr-hadoop-search article and the following two presentations from the two vendors   [slideshare id=35810888&doc=solr-2-140612162029-phpapp02] [slideshare id=24255985&doc=hadoopplussolrbigdatasearch-130715115557-phpapp02]   See also the Natural Language Processing and Sentiment Analysis for Retailers using HDP and ITC Infotech Radar article