Data type impacts

• Converting from decimal number to fixed decimal number can also marginally improve data compression and query performance.
• Power BI Desktop provides rich analysis capabilities for columns of the date data type including drill down hierarchies, visual calendar pickers for chart axis, custom date filtering logic in slicers, and calculations such as first and last date.

• Given these capabilities, as well as DAX functionality with Date data types, converting text and numeric types to date data types can provide significantly more options to develop Power BI content.
• Revising text data types to numeric data types per the example also impacts the DAX metrics that can be written. For example, if the Calendar Year column is stored as a text data type, the following DAX metric will fail due to type incompatibility:

• Revising calendar year to a whole number type avoids the need to use VALUE or FORMAT functions in each DAX measure.