title: Merging several taxonomy indexes for faceted search
body: <p>I am planing to change my existing lucene index to use the new facets introduced in lucene 3.4.0.</p>
  
  <p>Unfortunately, documentation is still a bit sparse, so I could not find an answer to my question:</p>
  
  <p>I create a relatively large index of 8 million books by dividing it into several smaller groups of documents, creating indices for them, and then joining them all together to one big index using <code>IndexWriter.addIndexes</code>. </p>
  
  <p>This allows the work to be split among several threads or even computers.</p>
  
  <p>I now would like to add faceted search capabilities to my index, but I have the following problem: How can I merge/add/join several taxonomy indexes as created by LuceneTaxonmyWriter?</p>