title: What are the main differences between search engines that should influence the decision as to which to use to search proprietary data?
body: <p>What are the main differences between search engines (DtSearch , Lucene.net, Sphinx, Google etc)  that should influence the decision as to which to use to search proprietary data?</p>
  
  <p>The data to be searched consists of presentation-free data that is marked up with metadata in the form of name/value pairs. We’re not interested in the format parsing abilities of the tools various. Also, the search results need to be well structured, presentation-free data that is amenable to aggregating with search results from other (similarly structured repositories. </p>
  
  <p>Some relevant search engine characteristics that need to inform the decision are listed below. Futther suggestions or description of experiences welcome.</p>
  
  <p>•   Cost
  •   Ease of use
  •   Can be configured to return specific tags only
  •   Can ‘identify’ specific terms give search results higher weighting for these results
  •   Fast &lt; 0.3seconds to return search results or %E6 records/documents
  •   Support tags with types (find weather=’sunny’ but not personality=sunny)
  •   Support weightings to give relevancy ranking
  •   Return results in ranked order by relevency
  •   Supports Synonyms
  •   Supports stemmings
  •   Supports Stop words
  •   Supports spelling corrections
  •   Amenable to parallelisation or index building (if index based)
  •   Fast to reindex (if index based)
  •   Fast to update index (if index based)
  •   Combine results from multiple indexes (if index based)
  •   Proximity checks: give higher relevance to words found close together</p>