DirectQuery with Tabular Models
DirectQuery is a deployment option available in Tabular Models, which allows the developer to use the relational data instead of the in-memory data in the model. This feature is still immature and needs to be understood to determine how this can be used.
Data sources
DirectQuery can only use SQL Server and SQL Server PDW databases as sources. No other relational or non-relational sources are supported including Oracle, SQL Server Analysis Services or files. In this case, using DirectQuery would be valuable if using a SQL Server data source and either real-time changes or large data volume are required in your solution.
Security
The role-based security in the Tabular Model is not supported with DirectQuery. The security within the data source, however, is supported.
Design limitations
Calculated columns are not supported in a table based on a DirectQuery source. While calculated measures and KPIs are supported, the DAX formula support is limited. It is possible...
