PR #430 added support for parsing MERGE INTO statements with WHEN MATCHED and WHEN NOT MATCHED clauses. While these clauses are sufficient for standard upsert operations, support for WHEN NOT MATCHED BY SOURCE is also required to express full synchronization or replacement semantics, such as deleting or updating target rows that no longer exist in the source.
PR #430 added support for parsing
MERGE INTOstatements withWHEN MATCHEDandWHEN NOT MATCHEDclauses. While these clauses are sufficient for standard upsert operations, support forWHEN NOT MATCHED BY SOURCEis also required to express full synchronization or replacement semantics, such as deleting or updating target rows that no longer exist in the source.