Hello All,
I'm looking for best practices or use cases for rebuilding an SSAS Multidimensional Cube in a Power BI Semantic Model. Specifically, I'm interested in guidance around data modeling and converting MDX queries to DAX.
Got few Ideas from Chat GPT
🔄 1. MDX to DAX Conversion
- Challenge: MDX (used in SSAS Multidimensional) and DAX (used in Tabular models) are fundamentally different in syntax and behavior.
- Issues:
- MDX supports complex calculations like scoped assignments and cell-level calculations, which are hard to replicate in DAX.
- DAX is row-context and filter-context driven, which requires rethinking logic.
- Tip: Focus on rewriting logic using DAX functions like CALCULATE, FILTER, SUMX, and VAR.
🧱 2. Data Modeling Differences
- Challenge: SSAS Multidimensional uses a cube structure with dimensions and measures, while Tabular models use relational tables and relationships.
- Issues:
- Hierarchies and attribute relationships need to be rebuilt manually.
- Many-to-many relationships are handled differently.
- Tip: Normalize your data model and use star schema design for optimal performance in Power BI.
📊 3. KPI and Calculated Members
- Challenge: KPIs and calculated members in MDX don’t directly translate to DAX.
- Issues:
- Calculated members often rely on MDX-specific context.
- KPIs need to be rebuilt using DAX measures and conditional formatting.
- Tip: Recreate KPIs using DAX measures and Power BI visual formatting options.
📁 4. Lack of Direct Feature Parity
- Challenge: Some SSAS features like named sets, custom actions, and cell calculations are not available in Tabular models.
- Tip: Consider redesigning reports or using workarounds with DAX and Power BI visuals.
🧪 5. Testing and Validation
- Challenge: Ensuring the migrated model produces the same results as the original cube.
- Tip: Use side-by-side comparisons of MDX vs. DAX outputs, and validate with business users.
🛠️ 6. Tooling and Automation
- Challenge: Limited automated tooling for MDX to DAX conversion.
- Tip: Use tools like Tabular Editor, DAX Studio, and SQL Server Profiler to assist with model building and performance tuning.
