In production environments, it can be hard to determine which mode (MODE_FILE,MODE_MMAP,MODE_MMAP_EXT, etc.) the reader is using withMODE_AUTO without experimenting (setting the mode explicitly), seeing which modes work, and then assumingMODE_AUTO is selected the mode you want (MODE_MMAP_EXT). Experimenting in production can cause problems.

It would be very helpful if themaxminddb.reader.Metadata object exposed the mode (string value) and whether that mode was auto or explicit (boolean). That way, a simple glance at the metadata could confirm that you've installed and configured everything correctly.