[taf2]

data-structures as a service.

need an atomic lock shared between multiple processes or servers (x)

need a set of unique values sorted by insertion time (x)

want to know the O(x) complexity of using any of the data-structures to design a system for scale (x)

need to notify multiple consumers of a modification ala pub-sub (x)

need to keep track of a stream of events for consumers (x)

need to do geo-spatial lookups (x)

oh and you want this thing to be durable to failure and easy to maintain (sentinel|cluster) (x)

redis is single process and easy to configure and understand that's my opinion of why it's so amazeballs.

[edit] unicode not supported so x instead