Why use SSAS Tabular when we have Power BI?

Managers, analysts, engineers and information workers, who use it, know that SQL Server Analysis Services Tabular (SSAS Tabular) is a valuable ICT asset. On the other hand, Power BI (PBI) is a great tool too that has a bit more functionality under its belt. Yet, there’s cases where SSAS Tabular might prove useful which we’ll detail in this blog.

Who does what?

Let’s look at the essence of both technologies. Simply put, with a single Power BI file you can:

  1. wrangle information from all kinds of sources into datasets,
  2. combine that information into a user-friendly data model,
  3. define powerful calculations on top of that model,
  4. allow users to easily discover information within that model,
  5. and provide stunning graphics derived from the model to improve insights.

SSAS Tabular, on the other hand, only takes care of the above mentioned points b and c. Now, don’t judge hastily and decide that Power BI is the only way to go for you. We will tell you why SSAS Tabular will interest you in a minute, but first we want to address briefly the points that are not covered by SSAS Tabular.

  • When using a SSAS Tabular model, you’ll need to wrangle information with other tools like SQL Server Integration Services, when working on premise, and Azure Data Factory, in the cloud. This requires extra skills that are not needed for PBI development. If these skills are already present in the organization, then this is not an issue.
  • Your users need tools to discover and consume information from the model. Luckily, Power BI and Excel easily connect to these SSAS Tabular models. This is not an issue, unless, in the case of Power BI, you have users connecting from Power BI Service which involves a PBI Pro license.
  • Moreover, Power BI, Excel and even other tools can be used to create graphics for your data enquiries on the SSAS Tabular model. Again, not an issue, but with the same remarks as before.

What does SSAS Tabular do better?

So far, SSAS may seem like an extra, somewhat unnecessary subsystem in your business intelligence process, but here are a few cases where it will help you overcome obstacles and things it does better than Power BI. The below benefits makes it worth looking into it for using it in your data efforts.

Future proof on your data size

The number of records loaded into Power BI files can grow quickly as your business goes on. However, some day, you will encounter a limit for the amount of data that can be compressed in the memory of your PBI files. Currently this limit is 1GB for a Standard Power BI version. The latest Power BI Premium version has no limit anymore, but that means your moving to another cost level. In SSAS Tabular, you are only limited by the size of the on-premise server’s RAM or by the amount of available Azure resources in case of cloud deployment.

Fine grained security control

SSAS Tabular gives you the possibility to define very precise and granular security rules on the consumable data. With row-level security rules, data rows can be shielded from target audiences like external users or employees from other departments depending on your business requirements.

Boost consistency

Developing Power BI files is easy and is a fun thing to do. If you work in a large organization, it will not take long before your infrastructure will host a ton of Power BI files. Within these files are models that differ from each other ever so slightly, because they were developed on a different day or by another person. Table and column names may be different across PBI files, for instance. In this plausible scenario, there is a bigger chance that calculations and KPIs will be named differently and even that their definitions are scripted in another way. We’re only human after all. These slightly differing models confuse your users when they look for the right file and data to use.

With SSAS Tabular, however, you can deploy a single model which can easily be queried from many Power BI files for analysis and reporting. The underlying base model will always be consistent. In a SSAS Tabular model, definitions of calculations, KPIs, and calculated columns as well, will be defined consistently for all end applications using them.

Easier management of security access

It may be time-consuming to change user access in case you have tens or hundreds of Power BI files located in on-premise file shares and in Power BI Service work folders. In the case of an SSAS Tabular model, you treat this information source as a database making it easier to regulate access. Just add or remove a user from a role that can access the Tabular model. Active Directory, or Azure AD, takes care of the rest.

Use other reporting tools

Power BI and Excel are just great tools to use with a SSAS Tabular model. They match perfectly.

But if you want to use other reporting tools, such as Reporting Services reports, Tableau, Pyramid, Spotfire, and the like, then you’re set with a SSAS Tabular Model.

Joey Tribbiani wants a pastrami sandwich, not a 7 course meal

A PBI model can expand over time to become really large. Some of its users may only need a portion of it, however, and are confronted with a model that is oversized and difficult for them to use. A SSAS Tabular model provides the possibility to define viewable parts of the model called “perspectives”. With these perspectives you can hide irrelevant portions of the model for certain target groups. This approach makes your users feel more “at home” in your model.

Translations of metadata

You may have important user groups operating in different languages, such as Dutch, English and French. SSAS Tabular has the ability to apply different languages for the names of the model, its tables, its columns and calculations, which can potentially be dynamically shown in reports based on the clients’ locale.

Best of both worlds

The seven arguments above may help you to decide whether SSAS Tabular has a place in your business intelligence pipeline, either on premise or in Azure. Using it in conjunction with Power BI can probably give you the best of both world. In any case, it’s a good idea to keep your eye on the tool. Both Analysis Services and Power BI (Premium) are solutions that are constantly being enhanced with new features. A fortune-teller may reveal that both will become one in a distant future.