As we countdown to the annual Lucene/Solr Revolution conference in Austin this October, we’re highlighting talks and sessions from past conferences. Today, we’re highlighting Trey Grainger’s session on multilingual search at CareerBuilder.

When searching on text, choosing the right CharFilters, Tokenizer, stemmers and other TokenFilters for each supported language is critical. Additional tools of the trade include language detection through UpdateRequestProcessors, parts of speech analysis, entity extraction, stopword and synonym lists, relevancy differentiation for exact vs. stemmed vs. conceptual matches, and identification of statistically interesting phrases per language. For multilingual search, you also need to choose between several strategies such as

1) searching across multiple fields,

2) using a separate collection per language combination, or

3) combining multiple languages in a single field (custom code is required for this and will be open sourced)

each with their own strengths and weaknesses depending upon your use case. This talk will provide a tutorial (with code examples) on how to pull off each of these strategies. We will also compare and contrast the different kinds of stemmers, discuss the precision/recall impact of stemming vs. lemmatization, and describe some techniques for extracting meaningful relationships between terms to power a semantic search experience per-language. Come learn how to build an excellent semantic and multilingual search system using the best tools and techniques Lucene/Solr has to offer!

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Trey Grainger is the Director of Engineering for Search & Analytics at and is the co-author of Solr in Action (2014, Manning Publications), the comprehensive example-driven guide to Apache Solr. His search experience includes handling multi-lingual content across dozens of markets/languages, machine learning, semantic search, big data analytics, customized Lucene/Solr scoring models, data mining, and recommendation systems. Trey is also the Founder of, a gluten-free search engine, and is a frequent speaker at Lucene and Solr-related conferences.

lucenerevolution-avatarJoin us at Lucene/Solr Revolution 2015, the biggest open source conference dedicated to Apache Lucene/Solr on October 13-16, 2015 in Austin, Texas. Come meet and network with the thought leaders building and deploying Lucene/Solr open source search technology. Full details and registration…