if (outputConstraint.arity() != schema.numFields()) throw new RuntimeException("Internal error: incorrect number of fields in constraint tuple.");
Tuple inputT = new Tuple(outputConstraint.arity());
ExampleTuple inputTuple = new ExampleTuple();
inputTuple.copyFrom(inputT);
for (int i = 0; i < inputTuple.arity(); i++) {
Datum d = outputConstraint.getField(i);
if (d == null) d = exampleTuple.getField(i);
inputTuple.setField(i, d);
}
if(inputTuple.equals(exampleTuple)) {