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 │
└───────────────────────────────────────┘
```
{
            chars = &col_from_string->getChars();
            offsets = &col_from_string->getOffsets();
        }
        else
        {
            chars = &col_from_fixed_string->getChars();
            fixed_string_size = col_from_fixed_string->getN();
        }
        size_t current_offset = 0;
        for (size_t i = 0; i < size; ++i)
        {
            size_t next_offset = std::is_same_v<FromDataType, DataTypeString> ? (*offsets)[i] : (current_offset + fixed_string_size);
            size_t string_size = std::is_same_v<FromDataType, DataTypeString> ? next_offset - current_offset - 1 : fixed_string_size;
            ReadBufferFromMemory read_buffer(&(*chars)[current_offset], string_size);
            if constexpr (exception_mode == ConvertFromStringExceptionMode::Throw)
            {
                if constexpr (parsing_mode == ConvertFromStringParsingMode::BestEffort)
                {
                    if constexpr (to_datetime64)
                    {
                        DateTime64 res = 0;
                        parseDateTime64BestEffort(res, vec_to.getScale(), read_buffer, *local_time_zone, *utc_time_zone);
                        vec_to[i] = res;
                    }
                    else
                    {
                        time_t res;
                        parseDateTimeBestEffort(res, read_buffer, *local_time_zone, *utc_time_zone);
                        vec_to[i] = res;