On Reading Fresher Snapshots in Parallel Snapshot Isolation

Abstract

In this paper we briefly present FPSI, a distributed transactional in-memory key-value store whose primary goal is to enable transactions to read more up-to-date (fresher) versions of shared objects than existing implementations of the well-known Parallel Snapshot Isolation (PSI) correctness level, in the absence of a synchronized clock service among nodes. FPSI builds upon Walter, an implementation of PSI well suited for social applications. The novel concurrency control at the core of FPSI allows its abort-free read-only transactions to access the latest version of objects upon their first contact to a node.