CODEWITHSUNDEEP
data-modelinghanadimensional-modeling
Siddharth
Siddharth

Reputation: 67

Using surrogate keys in SAP Hana

I am creating a dimensional data model for implementation in SAP Hana. In Dimensional modeling, having surrogate keys for dimension tables is mandatory, however I am told that in SAP Hana, we cannot define surrogate keys and have to depend on the natural keys for the dimensions. I have never come across this before, especially using natural keys for SCD dimensions is not possible.

Any suggestion on implementing surrogate keys in Hana will be great.

Upvotes: 1

Views: 943

Answers (1)

Lars Br.
Lars Br.

Reputation: 10388

SAP HANA supports, just like most other RDMBS, the automatic generation of surrogate (synthetic) keys. The feature name for this is IDENTITY column. There are also key value generating functions like SYSGUUID() available that generate guaranteed globally unique numbers.
This covers the feature for current databases, i.e. databases that represent only the most current state of information.

For the example you mentioned (slowly changing dimensions, SCD, type 2), you need to bring in a concept of during which timeframe any dimension entry is considered current. You need to create a temporal database. One way to do that is to add validFrom/validTo fields to your dimension tables and fill them accordingly during data loading. SAP HANA supports this type of modelling with a feature called temporal join that allows an easy match of fact data to a temporal dimension table.

Considering these features and the fact that SAP’s own data warehouse solution SAP BW/4 HANA manages slowly changing dimensions on SAP HANA, I’d say that the claim you heard is incorrect.

Upvotes: 3

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