**Describe the bug**

I have a table like:

```
CREATE TABLE test (
    time DateTime64(3)
    ...
) ENGINE = MergeTree()
PARTITION BY toStartOfInterval(time, INTERVAL 1 HOUR)
...
```

But when I search in `system.parts` it does not appear to have the `min/max` columns appropriately set?

```
partition:                             2020-06-01 01:00:00
min_date:                              1970-01-01
max_date:                              1970-01-01
min_time:                              1970-01-01 00:00:00
max_time:                              1970-01-01 00:00:00
```

I assume that if these were correctly set, doing a `select toStartOfInterval(time, interval 1 day), count()` type query would be pretty instant rather than trying to scan everything? I am guessing this is due to the `DateTime64` type in use?

Clickhouse 20.11.3.3

String codec_line;
        readEscapedStringUntilEOL(codec_line, *file_buf);
        ReadBufferFromString buf(codec_line);
        if (!checkString("CODEC", buf))
        {
            LOG_WARNING(storage.log, "Cannot parse default codec for part {} from file {}, content '{}'. Default compression codec will be deduced automatically, from data on disk", name, path, codec_line);
            default_codec = detectDefaultCompressionCodec();
        }
        try
        {
            ParserCodec codec_parser;
            auto codec_ast = parseQuery(codec_parser, codec_line.data() + buf.getPosition(), codec_line.data() + codec_line.length(), "codec parser", 0, DBMS_DEFAULT_MAX_PARSER_DEPTH);
            default_codec = CompressionCodecFactory::instance().get(codec_ast, {});
        }
        catch (const DB::Exception & ex)
        {
            LOG_WARNING(storage.log, "Cannot parse default codec for part {} from file {}, content '{}', error '{}'. Default compression codec will be deduced automatically, from data on disk.", name, path, codec_line, ex.what());
            default_codec = detectDefaultCompressionCodec();
        }
    }
}
CompressionCodecPtr IMergeTreeDataPart::detectDefaultCompressionCodec() const
{
    
    if (!isStoredOnDisk())
        return CompressionCodecFactory::instance().get("NONE", {});
    auto metadata_snapshot = storage.getInMemoryMetadataPtr();
    const auto & storage_columns = metadata_snapshot->getColumns();
    CompressionCodecPtr result = nullptr;
    for (const auto & part_column : columns)