@Override
 public void constraintDrop(KernelStatement state, UniquenessConstraint constraint)
     throws DropConstraintFailureException {
   state.locks().acquireExclusive(ResourceTypes.SCHEMA, schemaResource());
   schemaWriteDelegate.constraintDrop(state, constraint);
 }
 @Override
 public void constraintDrop(KernelStatement state, UniquenessConstraint constraint)
     throws DropConstraintFailureException {
   state.locks().acquireSchemaWriteLock();
   schemaWriteDelegate.constraintDrop(state, constraint);
 }