Important Terminology

In this chapter, we focused on various modeling concepts and how they’re used in SAP HANA. We introduced the following important terms:

• Views
  We started at by looking at views and realized that we can leverage the fact that SAP HANA already has all the data in memory, that the servers have lots of CPU cores available, and that SAP HANA runs everything in parallel. We therefore do not need to store the information in cubes and dimension tables, but can use views to generate the information when we need it. This also gives us the advantage of real-time results.
• Joins
  We have both normal database join types, like inner and left outer joins, and SAP HANA-specific types, like referential, text, temporal, and spatial joins. In the process, we also looked at the special case of self-joins and at dynamic joins as an optimization technique.
• Core Data Services (CDS)
  CDS provides a way to separate business semantics and intent from database operations.
• Cubes
  A cube consists of a data foundation with fact tables that contain the transactional data, linked to dimension tables that contain master data. The data foundation is linked to the dimension tables with star joins.
• Attributes and measures
  Attributes describe elements involved in a transaction. Transactional data that we can perform calculations on is called a measure and stored in the fact tables.
• Information views
  In SAP HANA, we take the concept of views to higher levels. We can create dimension tables and cubes as dimension views and star join views. Dimension views are attribute views and calculation views of type dimension. Star join views are analytic views and calculation views of type cube with star join. The final type of information view is the calculation view of type cube, which we can use to perform even more powerful processes.
• Modeling artifacts
  Inside our views, we can use unions, projections, aggregations, and ranking. Unions are quite flexible and can be used for a direct merge of result sets, or we can use a union with constant values to create report-ready result sets.