Each application developer desires to provide its users with consistent results and an always-available system despite failures. Boldly, the CALM theorem disagrees. It states that it is hard to design a system that is both consistent and available under network partitions; select at most two out of these three properties. One possible solution is to design coordination-free monotonic applications. However, a majority of real-world applications require coordination. We resolve this dilemma by conjecturing that partial progress is possible under network partitions. This partial progress ensures the system appears responsive to a subset of clients and achieves non-zero throughput during failures. To this extent, we present the design of our CASSANDRA consensus protocol that allows partitioned replicas to order client requests.
@article{arxiv.2501.00021,
title = {Did we miss P In CAP? Partial Progress Conjecture under Asynchrony},
author = {Junchao Chen and Suyash Gupta and Daniel P. Hughes and Mohammad Sadoghi},
journal= {arXiv preprint arXiv:2501.00021},
year = {2025}
}