How To Fix CFD_REGISTRY_CHECK104 - CDS View &1 must not use UNION operator

SAP Error Message - Details

• Message type: E = Error

• Message class: CFD_REGISTRY_CHECK - Custom Fields: Messages for Registry Check

• Message number: 104

• Message text: CDS View &1 must not use UNION operator

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message CFD_REGISTRY_CHECK104 - CDS View &1 must not use UNION operator ?

  The SAP error message CFD_REGISTRY_CHECK104 indicates that a Core Data Services (CDS) view is using the UNION operator, which is not allowed in certain contexts within the SAP system. This restriction is typically in place because the UNION operator can lead to performance issues and complications in data modeling, especially when dealing with certain types of data consumption or integration scenarios.
  Cause:
  The error occurs when a CDS view is defined with a UNION operator. This can happen if:
  
  The developer has combined multiple data sources using UNION in the CDS view definition.
  The CDS view is intended to be used in a context that does not support UNION operations, such as when it is being consumed by certain analytical tools or when it is part of a larger data model that requires specific performance characteristics.
  
  Solution:
  To resolve this error, you can take the following steps:
  
  
  Remove the UNION Operator: 
  
  Refactor the CDS view to eliminate the UNION operator. Instead, consider using JOINs or other methods to combine data from different sources.
  If you need to combine data from multiple sources, you might create separate CDS views for each source and then use a higher-level CDS view to join them if necessary.
  
  
  
  Use Alternative Approaches:
  
  If the data from the different sources is similar, consider using a JOIN instead of a UNION. This will allow you to combine the data without violating the restrictions.
  If the data sets are fundamentally different and need to be treated separately, consider creating separate CDS views and handling the combination at the application level or in the reporting layer.
  
  
  
  Check Documentation:
  
  Review the SAP documentation for CDS views to understand the limitations and best practices regarding the use of UNION and other operators.
  
  
  
  Testing:
  
  After making changes, test the CDS view to ensure that it behaves as expected and that the data is being retrieved correctly.
  
  
  
  Related Information:
  
  CDS Views: Core Data Services (CDS) is a framework for defining semantically rich data models in SAP. It allows for the creation of views that can be consumed by various SAP applications.
  Performance Considerations: Using UNION can lead to performance degradation, especially in large datasets, as it requires the system to combine results from multiple queries.
  SAP Notes and Community: Check SAP Notes or the SAP Community for any updates or additional guidance related to this error message, as there may be specific recommendations or patches available.
  
  By following these steps, you should be able to resolve the CFD_REGISTRY_CHECK104 error and ensure that your CDS view is compliant with SAP's requirements.