presto-main/src/main/java/io/prestosql/operator/scalar/StringFunctions.java/StringFunctions/rightPad
class StringFunctions:    @Description("pads a string on the right")
    @ScalarFunction("rpad")
    @LiteralParameters({"x", "y"})
    @SqlType(StandardTypes.VARCHAR)
    public static Slice rightPad(@SqlType("varchar(x)") Slice text, @SqlType(StandardTypes.BIGINT) long targetLength, @SqlType("varchar(y)") Slice padString)
    {
        return pad(text, targetLength, padString, text.length());
    }