Date Posted: 11/17/2020

Natacha Crooks, advised by Tisch University Professor Lorenzo Alvisi, has been awarded the 2020 SIGOPS Dennis M. Ritchie Doctoral Dissertation Award for her thesis "A Client-Centric Approach to Transactional Datastores." Crooks is now a faculty member in the Department of Electrical Engineering and Computer Science (EECS) at UC Berkeley.

The Dennis M. Ritchie Doctoral Dissertation Award was created in 2013 by ACM SIGOPS to recognize research in software systems and to encourage the creativity that Dennis Ritchie embodied, providing a reminder of Ritchie’s legacy and what a difference one person can make in the field of software systems research. This is an annual award presented in alternating years at SOSP and OSDI.


Modern applications must collect and store massive amounts of data. Cloud storage offers these applications simplicity: the abstraction of a failure-free, perfectly scalable black-box. While appealing, offloading data to the cloud is not without its challenges. These cloud storage systems often favour weaker levels of isolation and consistency. These weaker guarantees introduce behaviours that, without care, can break application logic. Offloading data to an untrusted third party like the cloud also raises questions of security and privacy. This thesis seeks to improve the performance, the semantics and the security of transactional cloud storage systems. It centers around a simple idea: defining consistency guarantees from the perspective of the applications that observe these guarantees, rather than from the perspective of the systems that implement them. This new perspective brings forth several benefits. First, it offers simpler and cleaner definitions of weak isolation and consistency guarantees. Second, it enables scalable implementations of existing guarantees like causal consistency. Finally, it has applications to security: it allows us to efficienctly augment transactional cloud storage systems with obliviousness guarantees.