```
$ 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.
*   or double: " if FormatSettings::CSV::allow_double_quotes is true;
  * - or string could be unquoted - this is determined by first character;
  * - if string is unquoted, then it is read until next delimiter,
  *   either until end of line (CR or LF),
  *   or until end of stream;
  *   but spaces and tabs at begin and end of unquoted string are consumed but ignored (note that this behaviour differs from RFC).
  * - if string is in quotes, then it will be read until closing quote,
  *   but sequences of two consecutive quotes are parsed as single quote inside string;
  */
void readCSVString(String & s, ReadBuffer & buf, const FormatSettings::CSV & settings);
template <typename Vector>
void readStringInto(Vector & s, ReadBuffer & buf);
template <typename Vector>
void readNullTerminated(Vector & s, ReadBuffer & buf);
template <typename Vector>
void readEscapedStringInto(Vector & s, ReadBuffer & buf);
template <bool enable_sql_style_quoting, typename Vector>
void readQuotedStringInto(Vector & s, ReadBuffer & buf);
template <bool enable_sql_style_quoting, typename Vector>
void readDoubleQuotedStringInto(Vector & s, ReadBuffer & buf);
template <bool enable_sql_style_quoting, typename Vector>
void readBackQuotedStringInto(Vector & s, ReadBuffer & buf);
template <typename Vector>
void readStringUntilEOFInto(Vector & s, ReadBuffer & buf);
template <typename Vector>
void readCSVStringInto(Vector & s, ReadBuffer & buf, const FormatSettings::CSV & settings);
template <typename Vector, typename ReturnType = void>
ReturnType readJSONStringInto(Vector & s, ReadBuffer & buf);
template <typename Vector>
bool tryReadJSONStringInto(Vector & s, ReadBuffer & buf)