title: Indexing engine
body: <p>I'm developing context discover system - which is mix of searching and suggestions. <br />
  Currently I'm looking for library for indexing. <br />
  After some investigation I stayed on <strong>Lucene</strong> and <strong>Terrier</strong> and found Indri not comfortable.</p>
  
  <p>What are the downsides of both? What problem I can meet while using them?</p>
  
  <p>Is it true that Terrier doesn't have incremental indexing (every time new document is added, I need to rebuild and reindex everything)?</p>
  
  <p>My requirements are:
   - easy adding new documents
   - easy score methods injection
   - quiet well defined model</p>
  
  <p>And one more thing: is Terrier still active? I haven't seen any update since 10/03/2010 <a href="http://terrier.org/docs/current/whats_new.html" rel="nofollow">terrier changelog</a></p>