Microsoft® SQL Server 2012 Unleashed

Columnstore Indexes

As mentioned before, for some types of queries, SQL Server can take advantage of a columnstore (columnar) layout to significantly improve query execution times (up to 50x performance in many cases). In particular, if you have a lot of filtering, aggregations, grouping, and star-join queries that touch few columns, but many rows, you are likely to want to look seriously at columnstore indexes.

The primary columnstore index concepts and characteristics you need to be aware of are as follows:

Columnar data format—Data is grouped and stored one column at a time, not in traditional row format.

Only the columns needed are read— ...