```
$ 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(current <= in.buffer().end());
    if (current < in.buffer().end())
        return true;
    saveUpToPosition(in, memory, current);
    bool loaded_more = !in.eof();
    
    
    assert(in.position() >= in.buffer().begin());
    assert(in.position() <= in.buffer().end());
    current = in.position();
    return loaded_more;
}
}