We’re also considering
TAP streams and
DCP streams
To accumulate copy of knowledge of those session events, and process that knowledge separately,
while still considering Couchbase as as “master storage”.
But that also costs: this time network bandwidth 
Because it’ll involve 100% of bytes to be transferred, while only a fraction of those really needed.
This hints at GSI approach with its projector+indexer, but that looks not to be ready for our needs.