```
$ 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.
{
    for (; *s; ++s)
    {
        if (buf.eof() || *buf.position() != *s)
            return false;
        ++buf.position();
    }
    return true;
}
bool checkStringCaseInsensitive(const char * s, ReadBuffer & buf)
{
    for (; *s; ++s)
    {
        if (buf.eof())
            return false;
        char c = *buf.position();
        if (!equalsCaseInsensitive(*s, c))
            return false;
        ++buf.position();
    }
    return true;
}
void assertString(const char * s, ReadBuffer & buf)