Tabular or multidimensional?

Question

Hello!

What are the differences between SSAS tabular and multidimensional data models?

How should I choose?

Is it feasible to choose a tabular model and then convert it into a multidimensional data model? If yes, how should I proceed?

Thank you in advance.

Answer 1

Hi @Annie999

In SSAS, tabular models and multidimensional data models are two very different models, and you need to choose them at the beginning of installation.

For the difference between the two, you can refer to this official document.

https://learn.microsoft.com/en-us/analysis-services/comparing-tabular-and-multidimensional-solutions-ssas?view=asallproducts-allversions

If you choose a tabular model, you want to migrate the data to the multidimensional data model after a while. I am afraid that this idea is unrealizable. You'll have to rebuild it, so you have to think about which data model to use in the first place.

Best regards,

Percy Tang

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Answer 2

While both multidimensional and tabular, can be queried effectively with both MDX and DAX, managed with XMLA, under the hood, they are implementations of not straight forwards translatable object models, AMO and TOM respectively.

To target your question, there is no seamless transition of the Visual Studio projects in any direction.

Key differences that can ease the decision:

• in multidimensional MDX is used for measures/calculations definitions, in tabular is DAX.
  which of them are developers familiar with, DAX may be easier to adopt, is continuously upgraded and developed as query language, MDX on other side have unique powers, like recursion.
• multidimensional can be only deployed as IaaS in cloud, tabular can go PaaS.
• tabular achieves higher levels of data compression, on numerical values especially.
• tabular engine aggregation query response times can be significantly shorter.
• the VS projects for tabular models are less complex and time consuming.

With that being said,
Power BI Premium, a SaaS, a superset of tabular, would be the preferred choice for greenfield projects.
It provides more features, cost and scalability benefits, plus projects can be created and deployed with Power BI Desktop, which can cut off the development time and has wider base of developers.

Answer 3

In 2023, you go Tabular unless you can positively prove that MD is the way to go, e.g. you only have SSAS 2012 licenses.