```
$ 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 ReturnType(true);
        }
        else
            
            return readIntTextImpl<time_t, ReturnType, ReadIntTextCheckOverflow::CHECK_OVERFLOW>(datetime, buf);
    }
    else
        return readDateTimeTextFallback<ReturnType>(datetime, buf, date_lut);
}
template <typename ReturnType>
inline ReturnType readDateTimeTextImpl(DateTime64 & datetime64, UInt32 scale, ReadBuffer & buf, const DateLUTImpl & date_lut)
{
    time_t whole;
    if (!readDateTimeTextImpl<bool>(whole, buf, date_lut))
    {
        return ReturnType(false);
    }
    DB::DecimalUtils::DecimalComponents<DateTime64> components{static_cast<DateTime64::NativeType>(whole), 0};
    if (!buf.eof() && *buf.position() == '.')
    {
        ++buf.position();
        
        for (size_t i = 0; i < scale; ++i)
        {
            if (!buf.eof() && isNumericASCII(*buf.position()))
            {
                components.fractional *= 10;
                components.fractional += *buf.position() - '0';
                ++buf.position();
            }