title: Forgot to close the Lucene IndexWriter after adding Documents to the index
body: <p>I had a program running for 2 days to build a Lucene index for around 160 million text files, and after the program ended, I tried searching the index and found the index was not correctly built, indexReader.numDocs() returned 0. I checked the index directory, it looked good, all the index data seemed to be there, the directory is 1.5 Gigabytes in size.</p>
  
  <p>I checked my code and found that I forgot to call indexWriter.optimize() and indexWriter.close(), I want to know if it is possible to re-optimize() the index so I don't need to rebuild the whole index from scratch? I don't really want the program to take another 2 days.</p>