For me, in a very simple way, the metrics layer is a subset of a semantic layer - as you pointed out where the semantic layer is covering a lot more use cases (like entities).
The data marts are materialisations of your data model. The semantic layer provides an interface to use your data model without needing knowledge of it.
For me, in a very simple way, the metrics layer is a subset of a semantic layer - as you pointed out where the semantic layer is covering a lot more use cases (like entities).
Yes it’s more like a single access point for data
What is in practice the difference between a semantic/metric layer and the old datamarts?
The data marts are materialisations of your data model. The semantic layer provides an interface to use your data model without needing knowledge of it.
Thanks for replying back David. But what exactly does that means in practice?
- Is a semantic layer a combination of tables or views that are exposed via API? Is it something else?
- Are DataMarts part of the Semantic Layer?
- Is the Semantic Layer coming after the dimensions and measures from the DataWarehouse?
I mean, what exactly is the semantic layer?
Thank you
The semantic layer allows you to access data from that data model materialised as tables.
It defines what the entities in the data model are in real world terms and how to access them.
Yes they often come with APIs to easily know what the semantic layer contains and request this data, but that is kind of a necessary bonus.
Check out cube.dev it’s a very good example
Thanks a lot David. I will.