title: Does a bitmap index create a replica of the original table?
body: <p>In this youtube tutorial <a href="http://www.youtube.com/watch?v=Qb7cmGBSHXo" rel="nofollow">here</a></p>
  
  <p>it seems that Bitmap index will always create a replica of the whole table when it creates the index. Because it creates the index and against each row, it puts 0 or 1. Is my understadning wrong?
  The otehr thing is that towards the end of the tutorial it seems that bitmap index cannot operate on a != operator.
  I thought that  <code>=</code> and <code>!=</code> seems the same to me from the POV of indexing. </p>