Hi vinni,
- 1.INNER JOIN: This type of join is used whenever we want to return all the values for at least one match in both the tables.
Referential Join: A referential join is similar to an inner join that assume that referential integrity is maintained between the two tables, which means that the left table always have a corresponding entry on the right table.
This can be seen as an optimized or faster inner join where the right table is not checked if no field from the right table is requested. Meaning that the Referential Joins will be only executed, when fields from both tables are requested. Therefore, if a field is selected from the right table it will act similar to inner join, and if no fields from the right table is selected it will act similar to a left outer join.
How it works?
Referential Join is only available while building Attribute View and Analytic View, it is not available in Calculation View.
Attribute View: It works as an inner join even if we don’t select any columns for the output from the right table.
Analytic View: It works as an inner join if we have columns from the both left and right table for the output.
The join will not be executed if we don’t have any columns from right table to the out. In this case execution is going to be just select on left table without any join condition and filter.
2.well if you did not have to perform any joins ( attribute views ) then i think , a calc view on column table or a calc view on analytical view would have been same . Joins and IF statements are very expensive in HANA . Join engine is very well optimised thus performing a join later at calc view seems to give a performance penalty.
3.Basically it is two types:
- 1.Graphical based
- 2.Script based
Calculated columns are created for Union operations or join operations or aggregation or projection purposes it is used.
If you want to create script based reports then we have to choose script based.
& it is used for complex calculations purposes it is used.