Flex-KV: Enabling high-performance and flexible KV systems

Even within one popular sub-category of "NoSQL" solutions - key-value (KV) storage systems - no one existing system meets the needs of all applications. We question this poor state of affairs. In this paper, we make the case for a flexible key-value storage system (Flex- KV) that can support both DRAM and disk-based storage, can act as an unreliable cache or a durable store, and operate consistently or inconsistently. The value of such a system goes beyond ease-of-use: While exploring these dimensions of durability, consistency, and availability, we find new choices for system designs, such as a cache-consistent memcached, that offer some applications a better balance of performance and cost than was previously available. Copyright 2012 ACM.