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 │
└───────────────────────────────────────┘
```
{
public:
    static constexpr auto name = Name::name;
    static constexpr bool to_decimal =
        std::is_same_v<ToDataType, DataTypeDecimal<Decimal32>> ||
        std::is_same_v<ToDataType, DataTypeDecimal<Decimal64>> ||
        std::is_same_v<ToDataType, DataTypeDecimal<Decimal128>> ||
        std::is_same_v<ToDataType, DataTypeDecimal<Decimal256>>;
    static constexpr bool to_datetime64 = std::is_same_v<ToDataType, DataTypeDateTime64>;
    static FunctionPtr create(const Context &) { return std::make_shared<FunctionConvertFromString>(); }