Search for: All records

This paper presents Pesto, a high-performance Byzantine Fault Tolerant (BFT) database that offers full SQL compatibility. Pesto intentionally forgoes the use of State Machine Replication (SMR); SMR-based designs offer poor performance due to the several round trips required to order transactions. Pesto, instead, allows for replicas to remain inconsistent, and only synchronizes on demand to ensure that the database remain serializable in the presence of concurrent transactions and malicious actors. On TPC-C, Pesto matches the throughput of Peloton and Postgres, two unreplicated SQL database systems, while increasing throughput by 2.3x compared to classic SMR-based BFT-architectures, and reducing latency by 2.7x to 3.9x. Pesto's leaderless design minimizes the impact of replica failures and ensures robust performance. 

This paper presents Pesto, a high-performance Byzantine Fault Tolerant (BFT) database that offers full SQL compatibility. Pesto intentionally forgoes the use of State Machine Replication (SMR); SMR-based designs offer poor performance due to the several round trips required to order transactions. Pesto, instead, allows for replicas to remain inconsistent, and only synchronizes on demand to ensure that the database remain serializable in the presence of concurrent transactions and malicious actors. On TPC-C, Pesto matches the throughput of Peloton and Postgres, two unreplicated SQL database systems, while increasing throughput by 2.3x compared to classic SMR-based BFT-architectures, and reducing latency by 2.7x to 3.9x. Pesto's leaderless design minimizes the impact of replica failures and ensures robust performance. 

Nakamoto’s consensus protocol works in a permissionless model and tolerates Byzantine failures, but only offers probabilistic agreement. Recently, the Sandglass protocol has shown such weaker guarantees are not a necessary consequence of a permissionless model; yet, Sandglass only tolerates benign failures, and operates in an unconventional partially synchronous model. We present Gorilla Sandglass, the first Byzantine tolerant consensus protocol to guarantee, in the same synchronous model adopted by Nakamoto, deterministic agreement and termination with probability 1 in a permissionless setting. We prove the correctness of Gorilla by mapping executions that would violate agreement or termination in Gorilla to executions in Sandglass, where we know such violations are impossible. Establishing termination proves particularly interesting, as the mapping requires reasoning about infinite executions and their probabilities. 

ScaleDB is a serializable in-memory transactional database that achieves excellent scalability on multi-core machines by asynchronously updating range indexes. We find that asynchronous range index updates can significantly improve database scalability by applying updates in batches, reducing contention on critical sections. To avoid stale reads, ScaleDB uses small hash indexlets to hold delayed updates. We use indexlets to design ACC, an asynchronous concurrency control protocol providing serializability. With ACC, it is possible to delay range index updates without adverse performance effects on transaction execution in the common case. ACC delivers scalable serializable isolation for transactions, with high throughput and low abort rate. Evaluation on a dual-socket server with 36 cores shows that ScaleDB achieves 9.5× better query throughput than Peloton on the YCSB benchmark and 1.8× better transaction throughput than Cicada on the TPC-C benchmark. 

ScaleDB is a serializable in-memory transactional database that achieves excellent scalability on multi-core machines by asynchronously updating range indexes. We find that asynchronous range index updates can significantly improve database scalability by applying updates in batches, reducing contention on critical sections. To avoid stale reads, ScaleDB uses small hash indexlets to hold delayed updates. We use in- dexlets to design ACC, an asynchronous concurrency control protocol providing serializability. With ACC, it is possible to delay range index updates without adverse performance effects on transaction execution in the common case. ACC delivers scalable serializable isolation for transactions, with high throughput and low abort rate. Evaluation on a dual- socket server with 36 cores shows that ScaleDB achieves 9.5× better query throughput than Peloton on the YCSB bench- mark and 1.8× better transaction throughput than Cicada on the TPC-C benchmark. 

Nakamoto’s consensus protocol works in a permissionless model, where nodes can join and leave without notice. However, it guarantees agreement only probabilistically. Is this weaker guarantee a necessary concession to the severe demands of supporting a permissionless model? This paper shows that, at least in a benign failure model, it is not. It presents Sandglass, the first permissionless con- sensus algorithm that guarantees deterministic agreement and termination with probability 1 under general omission failures. Like Nakamoto, Sandglass adopts a hybrid synchronous communication model, where, at all times, a majority of nodes (though their number is unknown) are correct and synchronously connected, and allows nodes to join and leave at any time. 

The shared log paradigm is at the heart of modern distributed applications in the growing cloud computing industry. Often, application logs must be stored durably for analytics, regulations, or failure recovery, and their smooth operation depends closely on how the log is implemented. Scalog is a new implementation of the shared log abstraction that offers an unprecedented combination of features for continuous smooth delivery of service: Scalog allows applications to customize data placement, supports reconfiguration with no loss in availability, and recovers quickly from failures. At the same time, Scalog provides high throughput and total order. The paper describes the design and implementation of Scalog and presents examples of applications running upon it. To evaluate Scalog at scale, we use a combination of real experiments and emulation. Using 4KB records, a 10 Gbps infrastructure, and SSDs, Scalog can totally order up to 52 million records per second. 

This paper presents the design and implementation of Obladi, the first system to provide ACID transactions while also hiding access patterns. Obladi uses as its building block oblivious RAM, but turns the demands of supporting transac- tions into a performance opportunity. By executing transac- tions within epochs and delaying commit decisions until an epoch ends, Obladi reduces the amortized bandwidth costs of oblivious storage and increases overall system through- put. These performance gains, combined with new oblivious mechanisms for concurrency control and recovery, allow Obladi to execute OLTP workloads with reasonable through- put: it comes within 5× to 12× of a non-oblivious baseline on the TPC-C, SmallBank, and FreeHealth applications. Latency overheads, however, are higher (70× on TPC-C).