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 (checkAndGetDataType<DataTypeString>(from_type_untyped.get()))
        {
            return [] (ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, const ColumnNullable *, size_t )
            {
                return ConvertImplGenericFromString::execute(arguments, result_type);
            };
        }
        else
        {
            if (cast_type == CastType::accurateOrNull)
                return createToNullableColumnWrapper();
            else
                throw Exception{"Conversion from " + from_type_untyped->getName() + " to " + to_type->getName() +
                    " is not supported", ErrorCodes::CANNOT_CONVERT_TYPE};
        }
    }
    WrapperType createArrayWrapper(const DataTypePtr & from_type_untyped, const DataTypeArray * to_type) const