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 [Clustered Columnstore Index](https://msdn.microsoft.com/en-us/library/gg492088.aspx) is an excellent match for my requirements, to improve read performance.

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 ?

[![enter image description here](https://i.stack.imgur.com/yTQY8.png)](https://i.stack.imgur.com/yTQY8.png)