In a MERGE INTO operation, what happens to new records with the same event_id as existing records?

In a MERGE INTO operation, new records that have the same event_id as existing records are ignored. The MERGE operation is typically used to synchronize two datasets, and it matches records based on specified keys (like event_id). When a match is found, the operation can perform actions such as updating existing records or deleting them, depending on the conditions provided.

When new records share the same key as existing ones, the behavior of the MERGE operation is defined by the instructions given in the specific conditions of the operation. If there is no specific instruction to handle these new records, they do not trigger an update or an insertion; they are simply overlooked. This ensures that existing records remain unchanged when a new record with the same unique identifier is encountered, preserving data integrity in scenarios where later data should not overwrite the existing ones without a defined rule.

Consequently, the other options, which suggest merging, error triggering, or replacing, do not accurately reflect the behavior of the MERGE operation without explicit handling of duplicate keys.