Proposal: Support for CTEs and Dynamic SQL in DirectQuery for SQL Server

[K-Data]

Proposal: Support for CTEs and Dynamic SQL in DirectQuery for SQL Server

Problem Description

Currently, when using DirectQuery in Power BI, certain features like CTEs (Common Table Expressions) and Dynamic SQL are limited or do not work as expected. This can significantly reduce flexibility, especially in complex queries or scenarios where temporary tables or dynamic query generation are necessary for performance or functionality.

Proposed Solution

Enable full support for CTEs and Dynamic SQL when using DirectQuery with SQL Server. This would involve:

• Allowing CTEs in DirectQuery
  • Full support for Common Table Expressions (CTEs) in queries that are sent from Power BI to SQL Server.
  • Allow multiple CTEs within a query to simplify complex data manipulations without needing to break the query into multiple steps.
  • Supporting Dynamic SQL
    • Enable the execution of dynamic SQL within DirectQuery queries.
    • Allow users to construct queries dynamically based on parameters, user selections, or filtering logic, without limitations.
    • Query Optimization
      • Work on ensuring that dynamic SQL and CTEs do not negatively affect query performance in DirectQuery mode.
      • Provide optimizations to ensure that queries with CTEs or dynamic SQL still return results efficiently from SQL Server.

        Use Cases

        • Complex Reporting Logic: When building complex queries that require temporary results or hierarchical data manipulations using CTEs.
        • Dynamic Reports: When users need to dynamically alter the query structure based on input parameters, filters, or slicers in Power BI.
        • Large Data Models: To efficiently manage and manipulate large datasets that require dynamic table generation or complex logic, which may otherwise require creating multiple views or stored procedures.

          Benefits

          • Improved Flexibility: Users can build more complex and flexible queries without limitations on SQL structure.
          • Advanced Reporting: Allow more sophisticated reports and data manipulations that are not possible with the current DirectQuery restrictions.
          • Better Performance: With proper optimization, dynamic queries and CTEs can help reduce the need for redundant tables or steps, improving performance.