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 │
└───────────────────────────────────────┘
```
{
                    if (requested_result_is_nullable)
                    {
                        
                        
                        
                        result_column = ConvertImpl<LeftDataType, RightDataType, NameCast, ConvertReturnNullOnErrorTag>::execute(
                            arguments, result_type, input_rows_count, scale);
                        return true;
                    }
                }
                result_column = ConvertImpl<LeftDataType, RightDataType, NameCast>::execute(arguments, result_type, input_rows_count, scale);
                return true;
            });
            
            if (!res)
            {
                if (wrapper_cast_type == CastType::accurateOrNull)
                {
                    auto nullable_column_wrapper = FunctionCast::createToNullableColumnWrapper();
                    return nullable_column_wrapper(arguments, result_type, column_nullable, input_rows_count);
                }
                else
                    throw Exception{"Conversion from " + std::string(getTypeName(type_index)) + " to " + to_type->getName() + " is not supported",
                        ErrorCodes::CANNOT_CONVERT_TYPE};
            }
            return result_column;
        };
    }
    WrapperType createAggregateFunctionWrapper(const DataTypePtr & from_type_untyped, const DataTypeAggregateFunction * to_type) const