One to many mapping between BMM layer and presentation layer

Sangeeta Pandey

Hello Experts,

May I know some examples of use cases when we need more than one subject area based on same BMM layer?

Why I am asking this question because- I was told by some SME that the good about using a semantic/BMM layer (regardless of if you use tables of views) is that you can build one data model for all reports. Reusability of one data model is much higher than when you build one view per report. It also helps you in building consistent reports and dashboards.t

I thought to know some examples of  use cases as per current BI industry.

Thanks,

[Deleted User]

Sangeeta Pandey wrote:May I know some examples of use cases when we need more than one subject area based on same BMM layer?

- Not all user groups use the same language in the corporation. You may need to adjust wording to their needs.

- Not everybody has the same requirements as to breadth and depth of available subject areas. Cutting them up into smaller pieces makes them easier to digest. Having to constantly navigate 50 dimension and 400 facts is tedious.

- Business Models can contain heterogeneous information

- Business Models can combine - for example - target and actual but sometimes you want to explicitly build things using actual or target data. Again, based on user populations and permissions.

etc

The list goes on for a long time but this may give you an idea.

Sangeeta Pandey wrote:I was told by some SME that the good about using a semantic/BMM layer (regardless of if you use tables of views) is that you can build one data model for all reports.

Yes, but no. Sure you can have one model but it becomes unmanageable and any mistake can kill everything in one go as well. I prefer producing a bit more metadata and having more freedom, overview, visibility and security. It's just metadata. Literally just some kilobytes of pure text. There's no code or anything. Cloning a business model takes 2 seconds with  a right-click.

Sangeeta Pandey wrote:Reusability of one data model is much higher than when you build one view per report.

Don't confuse the one with the other. "one data model" vs "one view" - the latter in OBI terms is just the complete antithesis of what the tool IS and DOES. Forget views, forget code. Think model.

I suggest you take some proper training to get all theses concepts explained to you by an expert in detail - an actual professional and some "me too I do OBI" and not those youtube channels who produce absolutely cringe-worthy RPDs.

Sangeeta Pandey wrote:It also helps you in building consistent reports and dashboards.t

Again: yes, but also no. As soon as self-service starts the "consistent" part goes out the window. All we can do is guide and help users. What they do with it is up to them. You have immensely lower garbage production in systems with a semantic model than in "solution" (cough cough) using SQL code, but users will do as users will do. They'll go left, right, up and down as far as they can push things.