Symptoms
A Cognos data module has been defined, including
- A custom data set
- The Changepoint package
A join has been defined between the package and the data set on an ID column, e.g. projectid:
When building a report or dashboard based on this data module, no data is returned.
Reason
Because Cognos internally uses different technologies when accessing the data set and the package, joining the two on ID columns (data type UNIQUEIDENTIFIER) is not possible. The reason is that in some places, the UNIQUEIDENTIFIER is displayed within { } and in other places it is not.
Workaround
As a workaround, a transformation can be applied to the ID column in the data set in the package:
Note: This has been tested with Changepoint V2017 and currently does not work with Changepoint 2020 due to a different Cognos version.