When creating a new project in SQL Server, one important decision to make is whether to use a Multidimensional or Tabular data model. While there is no clear-cut answer, there are several factors that can help guide your decision.
Multidimensional Model
The Multidimensional model is a traditional approach to data modeling in SQL Server. It offers several advantages:
- Support for complex calculations, scoping, and named sets
- Writeback support
- Access to many different external data sources
- Ability to handle extremely large datasets
- Support for features like actions, custom assemblies, custom rollups, custom drillthrough actions, linked objects, and translations
Tabular Model
The Tabular model is a newer data modeling approach in SQL Server. It offers several advantages over the Multidimensional model:
- Uses DAX (Data Analysis Expressions), which is easier to use than MDX (Multidimensional Expressions)
- Utilizes Vertipaq, a columnar in-memory engine that provides faster query performance
- Uses the existing relational model, eliminating the need to create a star schema
- Faster development time
- Less expensive in terms of time, resources, and skill requirements
- Ability to extend the data model without reprocessing the entire database
Choosing the Right Model
When deciding between the Multidimensional and Tabular models, consider the following factors:
- If you need to use DAX or Power View, you must use the Tabular model
- If your dataset is extremely large or requires complex modeling, the Multidimensional model may be a better choice
- If you need writeback support or access to many different external data sources, the Multidimensional model is necessary
- If you require extreme speed and consistently fast query time, the Tabular model is recommended
- If you need many-to-many relationships, the Multidimensional model is preferred
It’s important to note that you can create both types of models against the same data warehouse. For example, if you have already built a Multidimensional model but want to use Power View, you can create a Tabular cube to enable its use. Additionally, the Tabular model can be used for prototyping or self-service BI, allowing power business users to create a model that can later be enhanced by IT.
Ultimately, the choice between the Multidimensional and Tabular models depends on your specific requirements and preferences. Consider the factors discussed here and choose the model that best suits your needs.