title: Choose between HINCRBY and INCR for redis
body: <p>I have a forum and want to save and show topics' view count using redis. It seems I have two methods to do this: HINCRBY and INCR. Which should I choose? And why?( Given I have 10,000,000 topics in total )</p>
  
  <p>With HINCRBY I can use one key to keep all values, but the hash is big. But with INCR I'll have many keys.</p>