Concurrency in SAP RAP (RESTful ABAP Programming Model) refers to handling situations where multiple users try to modify the same data simultaneously — a classic case of the “lost update problem.”

SAP RAP provides built-in mechanisms to ensure data consistency, conflict detection, and safe updates, especially in Fiori apps or other UI/front-end scenarios.

We need to add the fields like timestamp in the database table.

Book table –>  changedat

Then add the annotation in the CDS view Entity –> interface

Now add eTag in the Behavior Definition

And use the eTag in the Behavior projection

Output : when 2 users try to modify the same data fields at same time.