```
$ 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.
{
    s.clear();
    readStringUntilWhitespaceInto(s, buf);
}
template void readNullTerminated<PODArray<char>>(PODArray<char> & s, ReadBuffer & buf);
template void readNullTerminated<String>(String & s, ReadBuffer & buf);
void readString(String & s, ReadBuffer & buf)
{
    s.clear();
    readStringInto(s, buf);
}
template void readStringInto<PaddedPODArray<UInt8>>(PaddedPODArray<UInt8> & s, ReadBuffer & buf);
template <typename Vector>
void readStringUntilEOFInto(Vector & s, ReadBuffer & buf)
{
    while (!buf.eof())
    {
        appendToStringOrVector(s, buf, buf.buffer().end());
        buf.position() = buf.buffer().end();
    }
}
void readStringUntilEOF(String & s, ReadBuffer & buf)
{
    s.clear();
    readStringUntilEOFInto(s, buf);
}
template <typename Vector>
void readEscapedStringUntilEOLInto(Vector & s, ReadBuffer & buf)