Without going to deeply we can say that the Tabular Model bring some advantage over the multidimensional model, this advantage are:
-We don’t need to have extensive knowledge about business intelligence to create a tabular model, to create a tabular model we only need to know about relational data base modeling to create a proper data model for our solution. Of course this depend of how far we need to go with our tabular model, the solution will more complex and will required more skill if you need to crate KPI, DAX calculation, etc. We can say that the skill required will be half way between power pivot skills and multidimensional model skills requirements.
-If you want to change the data model is too much easy and quickly implements change in a tabular model than in a multidimensional model. For a multidimensional model you probably need to redefine dimension, measures, relationships, partitions etc.
-The tabular model allows you to use PowerView as tool for creating reports using Excel o SharePoint interface. PowerView use DAX query to create reports, Tabular Model and PowerPivot use support DAX.
-Tabular model use a In-Memory architecture that improve query performance in some scenarios.
In the other hand we have multidimensional model that have some advantage to:
– The multidimensional model creates data aggregation in the multidimensional data base making the user query too much faster for complex cubes.
– We can use different kind of data architecture MOLAP (store aggregated data measures, and calculation for faster query’s), ROLAP (online query )or HOLAP (Hybrid approach).
– Other features that are supported out of the box for multidimensional model that are not supported for tabular model.
- Parent-child Hierarchies
- Many-to-many relationships
- Custom Assemblies
For more information go to Comparing Tabular and Multidimensional Solutions (SSAS)