presto-parser/src/main/java/io/prestosql/sql/SqlFormatter.java/Formatter/visitSampledRelation
class Formatter:        @Override
        protected Void visitSampledRelation(SampledRelation node, Integer indent)
        {
            process(node.getRelation(), indent);

            builder.append(" TABLESAMPLE ")
                    .append(node.getType())
                    .append(" (")
                    .append(node.getSamplePercentage())
                    .append(')');

            return null;
        }