title: high and low cardinality in Cassandra
body: <p>I keep coming across these terms: <code>high cardinality</code> and <code>low cardinality</code> in <code>Cassandra</code>.</p>
  
  <p>I don't understand what exactly they mean. what effects they have on queries and what is preferred.
  Please explain with example since that will be be easy to follow.</p>