```
$ 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.
assert(buf.hasPendingData());
    switch (*buf.position())
    {
        case '"':
            s.push_back('"');
            break;
        case '\\':
            s.push_back('\\');
            break;
        case '/':
            s.push_back('/');
            break;
        case 'b':
            s.push_back('\b');
            break;
        case 'f':
            s.push_back('\f');
            break;
        case 'n':
            s.push_back('\n');
            break;
        case 'r':
            s.push_back('\r');
            break;
        case 't':
            s.push_back('\t');
            break;
        case 'u':
        {
            ++buf.position();