SAP HANA: Interview Questions 41 through 50

41.What are the different engines available in HANA? 

In HANA there are mainly 3 types of engines. 

• Join Engine: used for attribute views 

• OLAP engine: used for analytic views 

• Calculation Engine: used for calculation views 

42. There is an analytic view which has calculated column defined. Which engine will be used when calling this view? 

By default analytic view is executed in OLAP engine.  

But this changes when analytic view has a calculated column.  If an analytic view has a calculated column then internally it is treated as calculation view and executed in calculation engine.  

43.If my Analytic View foundation is joined to attribute views, is both the OLAP and JOIN Engine used? 

Nope - during activation of the analytic views, the joins in the attribute views get 'flattened' and included in the analytic view run time object.  

Only the OLAP engine will be used then.  

44.We need to take UNION of 2 tables and then create a calculated column. Can we implement this in analytic view? 

Analytic view doesn’t support UNION. We need calculation view to implement this logic.  

45.Can we call an analytic view in another analytic view? 

NO. We cannot call an analytic view inside other analytic view.  

46.Can we call an analytic view or calculation view inside another calculation view? 

Yes. We can call all the views (attribute, analytic and calculation view) inside a calculation view.   

Note: Calculation views are composite views and can be used to combine other views. It can consume other Analytical, Attribute, other Calculation Views & tables. It can perform complex calculations not possible with other views.  

47.What are the different types of calculation view? Which one would you prefer? 

There are 2 types of calculation view possible. 

• Graphical calculation view 

• Scripted calculation view 

Graphical calculation views are created using the graphical editor. Scripted calculation views are created using SQL Editor.  
Graphical based calculation views offer better performance compared to SQL based calculation views. But in scenarios where graphical calculation views cannot implement business logic, we need to use scripted calculation view. 
Complex calculations which are not possible thru graphical approach, can be created using SQLScript. 

48.Explain what is schema mapping? 

Schema mapping is done when the physical schema in the target system is not the same as the physical schema in the source system. 

49.What is the system table used to save metadata and other information of Schema Mappings? 

The mapping between authoring and physical schemas is stored in the configuration table “_SYS_BI”.”M_SCHEMA_MAPPING”. 

50.What’s the purpose of Generating Time Data? 

Generate Time Data option under Quick Launch helps the user to generate the Time data so that it can be used for the creation of Time based Attribute Views. 
When you click Generate Time Data, you will be provided with two options Gregorian: Mainly the data will be generated based on From and To years along with the granularity (Hour, Minute, Second, Day, Month) mentioned. 
Fiscal: In this case, the time data will be generated based on the variant defined (some companies may use their own time period). Standard tables T005T, T005U, T009 and T009B in SAP HANA are required if you go for FISCAL type.