Value help issue for Constant column of UNION in a CV – HANA modeling

Scenario/Use case: In HANA modeling, a CV is created with an union node to combine 2 datasets and constant value column is created to differentiate the 2 data sets. When we are trying to apply the filter in a reporting tool(SAC or AO) on the constant column the value help doesn’t show the available values to filter.

This is a default behavior, it can be changed by the property “Empty Union Behavior” value in union node datasource mapping window.

SAP help documentation about Empty Union Behavior” click here SAP help, however it explains about the use case of whether datasource shall return values or not if no other columns from the data source are queried. But I will explain the use case of value help issue in this article.

I prepare 2 simple data sets in HANA CVs.

Combining them in a CV with union node, added a constant column with fixed values “O” for datasource 1 and “D” for datasource 2.

In the data preview of the final CV, Order Type is taken to filter area and click on value help to see available values and result is no record found.

This behavior is noticed in reporting applications like SAC or Analysis Office as well. Sometimes, it is very important apply the filter on this constant column.

Fix: That is due to property of Empty Union behavior as shown below, by default ‘No Row’ value is selected. With that, there is possibility of constant value is not getting populated for either of the datasets so value help is shown up.

Now we can change this setting to ‘Row with Constants’ and then value help in filter value will be shown automatically.

Thanks

Sreekanth