MERGE Restrictions

The following restrictions apply to updating and inserting table data with MERGE.

Constraint Enforcement

MERGE respects all enforced constraints in the target table. If the merge operation attempts to copy values that violate those constraints, MERGE returns with an error and rolls back the merge operation.

Caution: If you run MERGE multiple times using the same target and source table, each iteration is liable to introduce duplicate values into the target columns and return with an error.

Columns Prohibited from Merge

The following columns cannot be specified in a merge operation; attempts to do so return with an error: