SOme more info:
Like in Multiload:
for any error we check the Errortables mentioned above.
Do we such an arrangement in Merge Into?
Teradata (12.0 and later ) MERGE INTO syntax supports error tables. See the the topic "Logging MERGE Errors In an Error Table" in the SQL Data Manipulation Language volume in the Teradata user documentation set. The CREATE ERROR TABLE statement must be executed to create the error table before executing the MERGE statement.