```
$ echo '20210101,A' | clickhouse-local --input-format CSV --structure 'd Date, s String' --query "SELECT * FROM table"
Code: 27. DB::Exception: Cannot parse input: expected ',' before: '20210101,A\n': 
Row 1:
Column 0,   name: d, type: Date,   ERROR: text "20210101,A" is not like Date

: While executing ParallelParsingBlockInputFormat: While executing File. (CANNOT_PARSE_INPUT_ASSERTION_FAILED)
```

**How to solve**

Disambiguate while parsing by absense of separators between YYYY-MM-DD.
return true;
        }
        else
            return false;
    };
    UInt16 year = 0;
    if (!append_digit(year)
        || !append_digit(year) 
        || !append_digit(year) 
        || !append_digit(year)) 
        return error();
    if (!ignore_delimiter())
        return error();
    UInt8 month = 0;
    if (!append_digit(month))
        return error();
    append_digit(month);
    if (!ignore_delimiter())
        return error();
    UInt8 day = 0;
    if (!append_digit(day))
        return error();
    append_digit(day);
    date = LocalDate(year, month, day);
    return ReturnType(true);
}
template void readDateTextFallback<void>(LocalDate &, ReadBuffer &);
template bool readDateTextFallback<bool>(LocalDate &, ReadBuffer &);
template <typename ReturnType>
ReturnType readDateTimeTextFallback(time_t & datetime, ReadBuffer & buf, const DateLUTImpl & date_lut)