Data Storage and Queries Even if you use Power BI to create the majority of the analyses you need, you many times have to query and create reports directly from your data warehouse (DW). In addition, Power BI can operate in DirectQuery mode, where the data is stored in the DW, and Power BI serves as the client tool only. In short, you also have to know how to optimize Transact-SQL queries. So, what are the problems with analytical queries? Do you know how SQL Server can help you with them? Well, SQL Server can do it in many ways: with special joins and indices, with data compression, with window functions, but especially with columnar storage. Columnstore indices in SQL Server use the same storage as the semantic model in Power BI. How much do you gain from columnar storage? How much does the column cardinality influence on columnstore compression? Unlike in Power BI, you can update the columnstore indices in a SQL Server DW. Parts: •     Problems with analytical queries •     Bitmap filtered hash joins •     Special indexes •     Data compression and window functions •     Trans-relational model •     Columnar storage and batch processing •     Updating columnar storage •     Column cardinality influence