HANA Hot News: HANA建模时关于使用join的限制

Note 1702641 - Limitations for star schema modeling in HANA Modeler

 

Currently (SP04) the following rules do apply.

1. The central table of an analytic view is the table the measures point to. This is also called the fact table. There can only be one fact table in the data foundation of an analytic view. I.e. all measures must point to the same table.

2.The central table of an attribute view is the table the key attribute(s) point(s) to. All key attributes have to point to the same table in the data foundation of an attribute view (in case there is more than one key attribute).

3. If the logical join from an analytic view to an attribute view is a multi column join, all join conditions (lines) must point to the same physical table of the attribute view (this does not necessarily need to be the central table of the attribute view, although in the majority of the use cases it will be that table)

4. The cardinality can be 1:1, 1:n, n:1 n:m. Cardinality 1:n or n:m might lead to unexpected multiplication of fact table rows (a warning during deployment is shown in that case)

5.A join path is the set of joins and tables that links the fact table to an attribute / table. A table must not appear twice in any join path
Please refer to attached document "Join_issues_in_HANA_Modeler.pdf" explaining which use cases are allowed and which are not.