What is star schema ?
Star schema is the backbone of all data warehouse modelling be it SAP or Oracle . It is a fairly simple concept and is really important for any kind of analysis.
Star Schema in SAP HANA explained with an example
Master data table as below:
| Product Code | Description | Plant |
| SH | Shoe | US1 |
| CO | Coat | US1 |
| CA | Cap | DE1 |
Transaction data table as below:
| Product Code | Date(MM/DD/YYYY) | Revenue ($) |
| SH | 1/1/2016 | 100 |
| CO | 1/1/2016 | 200 |
| CA | 1/1/2016 | 300 |
| SH | 1/2/2016 | 100 |
| CO | 1/2/2016 | 200 |
| CA | 1/2/2016 | 300 |
Now, for analysis of the transaction data by product and description, we would be required to have connections between the master and transaction table. The overall data model would look as shown below:
Doesn’t look like much of a Star for a Star schema model right?
Well, that’s because we are doing a really small analysis here. Let’s assume our transaction data had Customer and Vendor details too. Also, we wanted to do more detailed time based analysis like Year/Month statistics from date.
Let’s see how that data model looks like.
This looks more like a star.. right? Well to be honest, it looks more like a 4-legged octopus to me but a Star schema sounds cooler so let’s go with that name.
To conclude, the star schema shows you how the backbone of your data models must look like. This will be much more clearer and fun when we actually start building data models in HANA and BW on HANA.