title: NOSQLDB categories..Need more info
body: <p>Are below the categories of NOSQL DB?</p>
  
  <p>key value ,
  columnar ,
  document &amp;
  graph</p>
  
  <p>I have idea on HBase, which is a columnar storage NOSQL DB; which stores data in key value pair. But what are document and graph type? Are these two also related to NOSQL DB?</p>
  
  <p>Please share some link/details where from I can get more info in document and graph type NOSQL DB.</p>