presto-verifier/src/main/java/io/prestosql/verifier/Validator.java/Validator/getResultsComparison
class Validator:    public String getResultsComparison(int precision)
    {
        List<List<Object>> controlResults = controlResult.getResults();
        List<List<Object>> testResults = testResult.getResults();

        if (valid() || (controlResults == null) || (testResults == null)) {
            return "";
        }

        Multiset<List<Object>> control = ImmutableSortedMultiset.copyOf(rowComparator(precision), controlResults);
        Multiset<List<Object>> test = ImmutableSortedMultiset.copyOf(rowComparator(precision), testResults);

        try {
            Iterable<ChangedRow> diff = ImmutableSortedMultiset.<ChangedRow>naturalOrder()
                    .addAll(Iterables.transform(Multisets.difference(control, test), row -> new ChangedRow(Changed.REMOVED, row, precision)))
                    .addAll(Iterables.transform(Multisets.difference(test, control), row -> new ChangedRow(Changed.ADDED, row, precision)))
                    .build();
            diff = Iterables.limit(diff, 100);

            StringBuilder sb = new StringBuilder();

            sb.append(format("Control %s rows, Test %s rows%n", control.size(), test.size()));
            if (verboseResultsComparison) {
                Joiner.on("\n").appendTo(sb, diff);
            }
            else {
                sb.append("RESULTS DO NOT MATCH\n");
            }

            return sb.toString();
        }
        catch (TypesDoNotMatchException e) {
            return e.getMessage();
        }
    }