21.2:

```
milovidov-desktop :) SELECT CAST(1111111111.222 AS DateTime64(3))

SELECT cast(1111111111.222, 'DateTime64(3)')

Query id: d10c8623-5c74-4a38-b535-a99f6af4d28d

┌─cast(1111111111.222, 'DateTime64(3)')─┐
│               2005-03-18 04:58:31.222 │
└───────────────────────────────────────┘
```

master:

```
milovidov-desktop :) SELECT CAST(1111111111.222 AS DateTime64(3))

SELECT cast(1111111111.222, 'DateTime64(3)')

Query id: cb4af967-a4ae-4df5-89ba-234d68675f93

┌─cast(1111111111.222, 'DateTime64(3)')─┐
│               2005-03-18 04:58:31.000 │
└───────────────────────────────────────┘
```
throw Exception("Wrong UUID conversion", ErrorCodes::CANNOT_CONVERT_TYPE);
                }
                else
                    result_column = ConvertImpl<LeftDataType, RightDataType, Name, SpecialTag>::execute(arguments, result_type, input_rows_count);
            }
            else
                result_column = ConvertImpl<LeftDataType, RightDataType, Name, SpecialTag>::execute(arguments, result_type, input_rows_count);
            return true;
        };
        if (isDateTime64<Name, ToDataType>(arguments))
        {
            
            const ColumnWithTypeAndName & scale_column = arguments[1];
            UInt32 scale = extractToDecimalScale(scale_column);
            if (to_datetime64 || scale != 0) 
            {
                if (!callOnIndexAndDataType<DataTypeDateTime64>(from_type->getTypeId(), call, ConvertDefaultBehaviorTag{}))
                    throw Exception("Illegal type " + arguments[0].type->getName() + " of argument of function " + getName(),
                                    ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
                return result_column;
            }
        }
        bool done;
        if constexpr (to_string_or_fixed_string)
        {
            done = callOnIndexAndDataType<ToDataType>(from_type->getTypeId(), call, ConvertDefaultBehaviorTag{});
        }
        else
        {