Improving DAX
In the previous chapter, we focused on the Import mode for the visual layer in Power BI, where a key point was to reduce the load on data sources by minimizing the complexity and number of queries that are issued to the semantic model.
In theory, a well-designed data model should not experience performance issues easily unless there are extremely high data volumes with tens of millions of rows or more. However, it is still possible to get poor performance with good data models due to the way DAX measures are constructed.
Learning the Data Analysis Expressions (DAX) basics may be considered easy by many people because it can be approached by people without a technical data background but who are comfortable writing formulas in a tool such as Microsoft Excel. However, mastering DAX can be challenging. This is because DAX is a rich language with multiple ways to achieve the same result. DAX code requires having knowledge of row context and filter context, which determines...
