I will dissect multiple internal binary JSON representations in several DBs (Mongo, Postgres, YDB, my own Sphinx, maybe more), and rant how they are so not great for querying.

My rant will also include a partial benchmark (of course), and a limited way out for the databases: as in, a few techniques I have tried and will be implementing in Sphinx, so that our BSON sucks on par or less. Spoiler alert: BSONs suck and nothing works really well for them, everything you thought is a lie (including the cake), hash tables suck, binary searches suck (even the clever ones and of course the naive ones), AVX2 sucks, maybe AVX512 sucks too (maybe I'll have the time to try that). As for the database users? Weeell, at least you will know how much your specific database sucks, why so, and what can the competition offer.