What tasks must you perform to prevent hidden date tables from being auto-generated in Power BI?

To prevent hidden date tables from being auto-generated in Power BI, it is essential to disable the Auto Date/Time feature. This feature automatically creates hidden date tables for any date fields in your data models, which can clutter the model and cause confusion.

When you enable "Mark as date table" for a specific calendar table, you are explicitly defining that table as your main date table. This prevents Power BI from creating any additional hidden date tables because it recognizes that you are already providing a comprehensive date range with your marked table. By setting your own date table, you ensure that it is used for date-related calculations, filtering, and visuals instead of relying on automatically generated tables.

Disabling Auto Date/Time in the Current File options or the Global options is indeed necessary to stop all hidden date tables from appearing in the first place. However, marking a specific table as the date table gives you control and ensures that your reporting is based on the defined and intended date structure. Therefore, marking your Calendar table is a practical step that clearly conveys to the Power BI engine that it should use this date table rather than creating other hidden ones.