The most important book is of course Relevant Search :). Once you plugin your data to Solr or Elasticsearch, you’re far from what your users expect from a search user experience! Taming Search teaches you how to optimize search results for your content, users, and their vernacular. It explores topics such as Lucene Internals, to appropriate use of search engine features, to machine learning – all to grow beyond dull, basic text matching that satisfies no one to deep search that focusses on a specific user experience.
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