```
$ 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.
{
    ++buf.position();
    if (buf.eof())
        throw Exception("Cannot parse escape sequence", ErrorCodes::CANNOT_PARSE_ESCAPE_SEQUENCE);
    char char_after_backslash = *buf.position();
    if (char_after_backslash == 'x')
    {
        ++buf.position();
        
        char hex_code[2];
        readPODBinary(hex_code, buf);
        s.push_back(unhex2(hex_code));
    }
    else if (char_after_backslash == 'N')
    {
        
        ++buf.position();
    }
    else
    {
        
        char decoded_char = parseEscapeSequence(char_after_backslash);