Upsert support in Spanner targets
Consider two common problems when writing to Spanner:
When performing an insert, a record with the same primary key already exists.
When performing an update, no record matches the specified primary key.
"Upsert" is an alternative that deals with both those issues at once. If a record with the specified primary key exists, it updates the record; otherwise, it performs an insert. Upserts are enabled by two properties:
When Execute Insert As Update is True, all INSERT operations will be converted to INSERT_OR_UPDATE. When an insert is not possible because an existing record has the specified primary key, the existing record will be updated.
When Execute Update As Insert is True, all UPDATE operations will be converted to INSERT_OR_UPDATE. When an update is not possible because no record with the specified primary key exists, a new record will be created.