Publications related to The PCL Theorem. Transactions cannot be Parallel, Consistent and Live

When is it safe to run a transactional workload under Read Committed?

The popular isolation level multiversion Read Committed (RC) exchanges some of the strong guarantees of serializability for increased transaction throughput. Nevertheless, transaction workloads can sometimes be executed under RC while still guaranteeing se ...

ASSOC COMPUTING MACHINERY2023

Deciding Robustness for Lower SQL Isolation Levels

Christoph Koch, Bas Ketsman

While serializability always guarantees application correctness, lower isolation levels can be chosen to improve transaction throughput at the risk of introducing certain anomalies. A set of transactions is robust against a given isolation level if every p ...

ASSOC COMPUTING MACHINERY2022

Efficient Protocols for Enforcing Causal Consistency in Geo-Replicated Key-Value Data Stores

Kristina Spirovska

Modern large-scale data platforms manage colossal amount of data, generated by the ever-increasing number of concurrent users. Geo-replicated and sharded key-value data stores play a central role when building such platforms. As the strongest consistency m ...

EPFL2020

Deciding Robustness for Lower SQL Isolation Levels

Christoph Koch, Bas Ketsman

While serializability always guarantees application correctness, lower isolation levels can be chosen to improve transaction throughput at the risk of introducing certain anomalies. A set of transactions is robust against a given isolation level if every p ...

ASSOC COMPUTING MACHINERY2020

The PCL Theorem: Transactions cannot be Parallel, Consistent, and Live

Rachid Guerraoui, Victor Bushkov, Panagiota Fatourou

We establish a theorem called the PCL theorem, which states that it is impossible to design a transactional memory algorithm that ensures (1) parallelism, i.e., transactions do not need to synchronize unless they access the same application objects, (2) ve ...

ASSOC COMPUTING MACHINERY2019

Fast General Distributed Transactions with Opacity

Aleksandar Dragojevic, Stanko Novakovic, Georgios Chatzopoulos

Transactions can simplify distributed applications by hiding data distribution, concurrency, and failures from the application developer. Ideally the developer would see the abstraction of a single large machine that runs transactions sequentially and neve ...

ASSOC COMPUTING MACHINERY2019

PaRiS: Causally Consistent Transactions with Non-blocking Reads and Partial Replication

Willy Zwaenepoel, Kristina Spirovska, Diego Didona

Geo-replicated data platforms are the backbone of several large-scale online services. Transactional Causal Consistency (TCC) is an attractive consistency level for building such platforms. TCC avoids many anomalies of eventual consistency, eschews the syn ...

IEEE COMPUTER SOC2019

PaRiS: Causally Consistent Transactions with Non-blocking Reads and Partial Replication

Willy Zwaenepoel, Kristina Spirovska, Diego Didona

Geo-replicated data platforms are at the backbone of several large-scale online services. Transactional Causal Consistency (TCC) is an attractive consistency level for building such platforms. TCC avoids many anomalies of eventual consistency, eschews the ...

2019

Distributed Transactional Systems Cannot Be Fast

Rachid Guerraoui, Willy Zwaenepoel, Panagiota Fatourou, Junxiong Wang, Diego Didona

We prove that no fully transactional system can provide fast read transactions (including read-only ones that are considered the most frequent in practice). Specifically, to achieve fast read transactions, the system has to give up support of transactions ...

2019

Locking Timestamps versus Locking Objects

Rachid Guerraoui, Tudor Alexandru David, Junxiong Wang

We present multiversion timestamp locking (MVTL), a new genre of multiversion concurrency control algorithms for serializable transactions. The key idea behind MVTL is simple: lock individual timestamps instead of locking objects. After presenting a generi ...

ASSOC COMPUTING MACHINERY2018

Universally Scalable Concurrent Data Structures

Tudor Alexandru David

The increase in the number of cores in processors has been an important trend over the past decade. In order to be able to efficiently use such architectures, modern software must be scalable: performance should increase proportionally to the number of all ...

EPFL2017

Program Analysis and Compilation Techniques for Speeding up Transactional Database Workloads

Mohammad Dashti Rahmat Abadi

There is a trend towards increased specialization of data management software for performance reasons. The improved performance not only leads to a more efficient usage of the underlying hardware and cuts the operation costs of the system, but also is a ga ...

EPFL2017

Safety, Liveness and Parallelism in Concurrent Computing

Victor Bushkov

The correctness of a shared object, which can be accessed by several processes concurrently, is specified through two different kinds of properties - safety and liveness. When implementing a shared object it is important to specify its correctness in a suc ...

EPFL2015

Consistency Models in Distributed Systems with Physical Clocks

Jiaqing Du

Most existing distributed systems use logical clocks to order events in the implementation of various consistency models. Although logical clocks are straightforward to implement and maintain, they may affect the scalability, availability, and latency of t ...

EPFL2014

Clock-SI: Snapshot Isolation for Partitioned Data Stores Using Loosely Synchronized Clocks

Willy Zwaenepoel, Sameh Mohamed Elnikety, Jiaqing Du

Clock-SI is a fully distributed protocol that implements snapshot isolation (SI) for partitioned data stores. It derives snapshot and commit timestamps from loosely synchronized clocks, rather than from a centralized timestamp authority as used in current ...

2013

Scalability of write-ahead logging on multicore and multisocket hardware

Anastasia Ailamaki, Radu Ioan Stoica, Frederick Ryan Johnson, Manoussos Gavriil Athanassoulis, Ippokratis Pandis

The shift to multi-core and multi-socket hardware brings new challenges to database systems, as the software parallelism determines performance. Even though database systems traditionally accommodate simultaneous requests, a multitude of synchronization ba ...

2012

Transactions in the Jungle

Rachid Guerraoui, Vasu Singh, Michal Kapalka

Transactional memory (TM) has shown potential to simplify the task of writing concurrent programs. Inspired by classical work on databases, formal definitions of the semantics of TM executions have been proposed. Many of these definitions assumed that acce ...

Acm Order Department2010

Aether: A scalable approach to logging

Anastasia Ailamaki, Radu Ioan Stoica, Frederick Ryan Johnson, Manoussos Gavriil Athanassoulis, Ippokratis Pandis

The shift to multi-core hardware brings new challenges to database systems, as the software parallelism determines performance. Even though database systems traditionally accommodate simultaneous requests, a multitude of synchronization barriers serialize ...

2010

On the Correctness of Transactional Memory

Rachid Guerraoui, Michal Kapalka

Transactional memory (TM) is perceived as an appealing alternative to critical sections for general purpose concurrent programming. Despite the large amount of recent work on TM implementations, however, very little effort has been devoted to precisely def ...

2008

A formal analysis of the deferred update technique

Fernando Pedone, Rodrigo Malta Schmidt

The deferred update technique is a widely used approach for building replicated database systems. Its fame stems from the fact that read-only transactions can execute locally to any single database replica, providing good performance for workloads where tr ...

Springer-Verlag New York, Ms Ingrid Cunningham, 175 Fifth Ave, New York, Ny 10010 Usa2007