How To Fix USMD1090 - Entity type &1, relationship &2: Leading entity type &3 is not unique

SAP Error Message - Details

• Message type: E = Error

• Message class: USMD1 - Datenmodel

• Message number: 090

• Message text: Entity type &1, relationship &2: Leading entity type &3 is not unique

What causes this issue?

The <LS>From-entity type </>&V4& has the leading entity type &V3&, which
needs to be unique in the context of the <LS>To-entity type </>&V1&:
&V3& must be either a part of the key of &V1& or must be assigned
through exactly one relationship of the type <LS>Referencing</> to the
entity type &V1&.

System Response

The data model cannot be activated.

How to fix this error?

Adjust the data model so that the condition described above is
fulfilled.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message USMD1090 - Entity type &1, relationship &2: Leading entity type &3 is not unique ?

  The SAP error message USMD1090 typically occurs in the context of SAP Master Data Governance (MDG) when there is an issue with the uniqueness of the leading entity type in a relationship. This error indicates that the system has detected that the leading entity type specified in the relationship is not unique, which can lead to ambiguity in data processing.
  Cause:
  The error message USMD1090 is triggered when:
  
  Non-Unique Leading Entity: The leading entity type (e.g., a business partner, material, etc.) is not unique in the context of the relationship being defined. This means that there are multiple instances of the leading entity that could potentially relate to the same instance of the dependent entity.
  Incorrect Configuration: The configuration of the relationship in the data model may not be set up correctly, leading to multiple instances of the leading entity being associated with the same dependent entity.
  Data Integrity Issues: There may be data integrity issues where the data model does not enforce uniqueness constraints properly.
  
  Solution:
  To resolve the USMD1090 error, you can take the following steps:
  
  
  Check Data Model Configuration:
  
  Review the configuration of the relationship in the data model. Ensure that the leading entity type is defined correctly and that it is supposed to be unique in the context of the relationship.
  If necessary, adjust the relationship configuration to ensure that the leading entity is unique.
  
  
  
  Data Cleanup:
  
  Check the existing data for duplicates of the leading entity type. If duplicates exist, you may need to clean up the data to ensure that each leading entity is unique.
  Use transaction codes like SE16 or SE11 to analyze the underlying tables and identify duplicates.
  
  
  
  Adjust Business Logic:
  
  If the business logic allows for multiple instances of the leading entity, consider whether the relationship should be redefined to accommodate this scenario.
  You may need to create a new relationship type or modify the existing one to handle the non-unique situation appropriately.
  
  
  
  Consult Documentation:
  
  Refer to SAP documentation or help resources for guidance on configuring relationships in MDG. This can provide insights into best practices and common pitfalls.
  
  
  
  Testing:
  
  After making changes, test the configuration to ensure that the error no longer occurs and that the relationships function as intended.
  
  
  
  Related Information:
  
  SAP Notes: Check for any relevant SAP Notes that may address this specific error or provide additional troubleshooting steps.
  MDG Configuration Guides: Review the configuration guides for SAP Master Data Governance to understand how to properly set up entity types and relationships.
  Community Forums: Engage with SAP community forums or support channels for additional insights and experiences from other users who may have encountered the same issue.
  
  By following these steps, you should be able to identify the root cause of the USMD1090 error and implement a solution to resolve it.