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 │
└───────────────────────────────────────┘
```
WrapperType && wrapper_function_, const char * name_, std::optional<Diagnostic> diagnostic_)
            : wrapper_function(std::move(wrapper_function_)), name(name_), diagnostic(std::move(diagnostic_)) {}
    String getName() const override { return name; }
protected:
    ColumnPtr execute(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
    {
        
        ColumnsWithTypeAndName new_arguments{arguments.front()};
        if (arguments.size() > 2)
            new_arguments.insert(std::end(new_arguments), std::next(std::begin(arguments), 2), std::end(arguments));
        try
        {
            return wrapper_function(new_arguments, result_type, nullptr, input_rows_count);
        }
        catch (Exception & e)
        {
            if (diagnostic)
                e.addMessage("while converting source column " + backQuoteIfNeed(diagnostic->column_from) +
                             " to destination column " + backQuoteIfNeed(diagnostic->column_to));
            throw;
        }
    }
    bool useDefaultImplementationForNulls() const override { return false; }