Referential Join
This Join type is possible in Calculation Views. As per SAP, referential join offers better optimization. Let’s understand how does it work.
This join is optimized because the join is only carried out when necessary. When the join is carried out, it works as “Inner Join”. This is a good starting point. Imagine we have two tables – Sales Order and Customer.
If these two tables are joined (inner join) then the output will show rows that exist in both the tables. In the SAP Business Suite, the customer number existing in the Sales Order table must also exist in the Customer table. We also know the Cardinality, in this case, is N:1.
Imagine, we only need the Sales Order number, Total Weight and Total Value in the output from these joined tables. In this case, if the join is not carried out, then also the result will not change. In order to make it dynamic, we can change the inner join with the referential join. So, the referential join will work even if the Customer Name is required in the output but the join will be pruned if only the columns from the Sales Order table are requested.
Referential Join is dependent on cardinality and something called “integrity constraint”.
Imagine our Sales Order and Customer tables have cardinality N:M, then the join cannot be pruned even if the columns of the Sales Order table are requested. That is because – rows of the Sales Order table will repeat for a different combination of customers.
Integrity constraint – is defined as left, right or both. In this example, it is left. Every record in the sales order table has at least one record in the customer table. If only columns of the customer table are requested then the join cannot be pruned.
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