I read blogs on dgraph and badger.

badger is based on WISCKEY paper, this implies two things

key => sorted, stored in LSM trees, persisted as “sst” files (SSTables)

values => append only logs, persisted as “vlog” files

And posting list means key-value pairs.

So when dgraph claims that posting list is sorted, what exactly is sorted? I assume only keys, and not values.

Or are values sorted? If yes, is this a dgraph logic implemented on top of badger?

I hope values aren’t sorted, if yes, the the whole point of sequential IO for values, as presented in WISCKEY paper is lost