Difference between Data View, Association View and E-R Model

edited October 2019 in Data Modeling

Hi to all,

I've attended to SAP Tech Ed Barcellona, and I've partecipated in many workshops. I feel that SAP DWHC needs to clear his strategy, and define correctly a purpose for all the tools inside.

So, what I've understood:

1) SAP DWHC should be an open system, and SAP is working on an Open Schema SQL, that should let other tools to consume SAP DWHC, with also query builder capabilities (see Power BI or Tableau as examples).

2) In the meanwhile, the only tool is SAC, which works only on a single dataset. That's why, in order to show it in a story, you need a fact table with at least a measure

3) Only data views (at the moment) are seen by SAC. I've tried with the E-R Model, to set a table as a Fact, but still it doesn't get seen.

3.1) E-R Models are a great way for IT to define a DWH, and then let Business Modelers to make different data views starting from E-R Models, in order to consume data from SAC. However I HOPE you'll let derive fact tables from ER models (i.e.: if I create a view from an E-R and I drag a fact table, the output should be a fact table, IMHO).

3.2) What's still unclear to me is the Association View. At first I got that Data View was useful for defining dimensions, and the association view to define a Star Schema, with other dimensions and a fact connected...but that's not the case. In fact, if I define the output of a Data View as Fact table, and then in the Association View I connect another table, defined as a Dimension, and I go to SAC...I don't get any of the attributes of the dimension table.

Can you please provide a correct and complete description of the purpose of the Data View, Association View, E-R Model? Am I wrong?

Best regards


Daniele

Best Answer

  • Accepted Answer

    Hello Daniele,

    an SAC Story can only created by connecting to a Data-View of Type Fact, as the Story requires TODAY at least a single Measure In the Data-View - where Measures are only supported with Data-Views of Type Fact. We need to enable SAC Stories to support Master Data Reporting - w/o Measures - connecting to Data-Views of type Dimension.

    The ER-Model represents the Conceptual Model using Associations to connect the entities. Data-Views can be created from the ER Model entities by re-using the Associations as suggested Join options on how to define the real DB-Joins (ELT). ER-Model should be leveraged to create the Applikation Entities as part of Plan / Model phase - where Data-Views represent the Implementation on how data should be accessed and processed.

    The Association View will most probably disappear - only leverage and enhance the ER-Model capabilities.

    Pls feel free to comment.


    Tks Axel

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