```
$ 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.
if (buf.count() - initial_pos + 1 >= std::numeric_limits<T>::max_digits10)
                    {
                        if (negative)
                        {
                            T signed_res = -res;
                            if (common::mulOverflow<T>(signed_res, 10, signed_res) ||
                                common::subOverflow<T>(signed_res, (*buf.position() - '0'), signed_res))
                                return ReturnType(false);
                            res = -static_cast<UnsignedT>(signed_res);
                        }
                        else
                        {
                            T signed_res = res;
                            if (common::mulOverflow<T>(signed_res, 10, signed_res) ||
                                common::addOverflow<T>(signed_res, (*buf.position() - '0'), signed_res))
                                return ReturnType(false);
                            res = signed_res;
                        }
                        break;
                    }
                }
                res *= 10;
                res += *buf.position() - '0';
                break;
            }
            default:
                goto end;