When you have to run an OLAP query that perform sum of Sales in table with where clause in Country=’US’.
Select Sum(Sales) from FCT_SALES where Country=’US’;
It storage type is a column based storage in memory cells all the values for Sales will come together in database and when an aggregation ‘Sum’ is performed it will be much faster as compared to an OLTP query.
If table is row based storage with values are stored with different data types coming together and a ‘Sum’ aggregation is performed, it will too tough to find values for ‘Sales’ column.
In graph, column based tables show the value of Sales in the database and shows it is easy to perform calculations.