Using AdventureworksDW2016CTP3 we will work with the FactResellerSalesXL table which has 11.6 million rows in it. The simple query we will use as a demo just selects the ProductKey and returns some aggregations grouping them by the different product keys.
First, we will run the query with no existing columnstore index and only using the current clustered rowstore (normal) index. Note that I turned on SET STATISTICS IO and TIME on. These two SET statements will help us better illustrate the improvements provided by the columnstore index. SET STATISTICS IO displays statistics on the amount of page activity generated by the query. It gives you important details such as page logical reads, physical reads, scans, and lob reads both physical and logical. SET STATISTICS TIME displays the amount of time needed to parse, compile, and execute each statement in the query. The output shows the time in milliseconds for each operation to complete. This allows you to really see, in numbers, the differences.
Click through for the example.