Upsert Destination Error: System.Exception: Looks like source data has duplicate rows (same key multiple times)

[pankaj]

When utilizing the Upsert Destination, you might come across the following error:

Upsert Destination Error: System.Exception: Looks like source data has duplicate rows (same key multiple times).

The MERGE statement attempted to UPDATE or DELETE the same row more than once. This happens when a target row matches more than one source row. A MERGE statement cannot UPDATE/DELETE the same row of the target table multiple times. Refine the ON clause to ensure a target row matches at most one source row, or use the GROUP BY clause to group the source rows.
at ZappySys.PowerPack.Adapter.UpsertDestination.UpsertComponentBase.ProcessInput(Int32 inputID, PipelineBuffer buffer)
at Microsoft.SqlServer.Dts.Pipeline.ManagedComponentHost.HostProcessInput(IDTSManagedComponentWrapper100 wrapper, Int32 inputID, IDTSBuffer100 pDTSBuffer, IntPtr bufferWirePacket)

Cause:

The error in the MERGE statement due to duplicate rows typically occurs when the source or target tables have duplicate records that match the specified conditions in the MERGE statement. The MERGE operation requires a clear and unique mapping between source and target rows, and the presence of duplicates can lead to ambiguity in determining which records to update, insert, or delete.

To address this issue:

Here are several options to address and resolve this error (outlined below):

Option #1: Identify and Remove Duplicates. Attempt to cleanse the source data to eliminate any occurrences of duplicate keys.

Option #2: Consider configuring the Duplicate Handling option (found on the Advanced Tab) to a setting other than None, based on your preferences.

Option #3: Explore using distinct Key columns to prevent the detection of duplicates.