title: clustered columnstore index is slow
body: <p>I have a quite big table with 400 columns and 100,000 rows.
  When I select all columns, the query is very slow (~7500ms).
  There is only a primary key set on 3 columns.
  I don't care about the speed of insert/update, this table is mostly for reads.
  I was reading about how <a href="https://msdn.microsoft.com/en-us/library/gg492088.aspx" rel="nofollow noreferrer">Clustered Columnstore Index</a> is an excellent match for my requirements, to improve read performance.</p>
  
  <p>So I tried with the clustered columnstore index and the speed is almost the same (~7000ms). I really expected a much higher improvement. Am I missing something ?</p>
  
  <p><a href="https://i.stack.imgur.com/yTQY8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yTQY8.png" alt="enter image description here"></a></p>