Explore efficient mutual subscriber queries
Goals
We able to return a list of users that are also subscribed to a channel
Considerations
- Subscriptions lists are capped at 5k so are efficient to query
- Subscriber lists have no cap and can we very large
- Cassandra doesn't have intersect queries
- Cassandra
WHERE IN (...)
is very inefficient - Redis intersects are very fast, however loading of the data may be complicated