[kleineshertz]

Regarding using in-memory storage. Early prototype of Capillaries used Redis for storage and the performance was stellar. I decided to drop it for two reasons. First, indexing mechanism required a root-level sorted set, and Redis cannot partition it. Second, most of intermediate data is supposed to be available until the end of the run, which means hours, and I was not sure that typical Capillaries users would agree to carry the cost of providing so much RAM vs disk space. Am I willing to return to the discussion about replacing Cassandra with some in-memory storage? Maybe.