that's why numeric parts of the keys have to be encoded
as a fixed length, "big-endian" ordered strings, so
string sorting will also sort the numeric keys correctly.
this also assumes room ids don't contain the "|" character,
we should probably escape the separator at some point.
as a preparation to serialize the eventIndex and fragmentId
as a 8 character string, part of a concatenated string PK,
as lumia doesn't support array keys.
