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Publications

Publications by Ana Nunes Alonso

2013

Improving transaction abort rates without compromising throughput through judicious scheduling

Authors
Nunes, A; Pereira, J;

Publication
Proceedings of the ACM Symposium on Applied Computing

Abstract
Althought optimistic concurrency control protocols have increasingly been used in distributed database management systems, they imply a trade-off between the number of transactions that can be executed concurrently, hence, the peak throughput, and transactions aborted due to conflicts. We propose a novel optimistic concurrency control mechanism that controls transaction abort rate by minimizing the time during which transactions are vulnerable to abort, without compromising throughput. Briefly, we throttle transaction execution with an adaptive mechanism based on the state of the transaction queues while allowing out-of-order execution based on expected transaction latency. Preliminary evaluation shows that this provides a substantial improvement in committed transaction throughput. Copyright 2013 ACM.

2013

AJITTS: Adaptive just-in-time transaction scheduling

Authors
Nunes, A; Oliveira, R; Pereira, J;

Publication
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Abstract
Distributed transaction processing has benefited greatly from optimistic concurrency control protocols thus avoiding costly fine-grained synchronization. However, the performance of these protocols degrades significantly when the workload increases, namely, by leading to a substantial amount of aborted transactions due to concurrency conflicts. Our approach stems from the observation that when the abort rate increases with the load as already executed transactions queue for longer periods of time waiting for their turn to be certified and committed. We thus propose an adaptive algorithm for judiciously scheduling transactions to minimize the time during which these are vulnerable to being aborted by concurrent transactions, thereby reducing the overall abort rate. We do so by throttling transaction execution using an adaptive mechanism based on the locally known state of globally executing transactions, that includes out-of-order execution. Our evaluation using traces from the industry standard TPC-E workload shows that the amount of aborted transactions can be kept bounded as system load increases, while at the same time fully utilizing system resources and thus scaling transaction processing throughput. © 2013 IFIP International Federation for Information Processing.

2017

Towards new data management platforms for a DSO as market enabler – UPGRID Portugal demo

Authors
Alonso, A; Couto, R; Pacheco, H; Bessa, R; Gouveia, C; Seca, L; Moreira, J; Nunes, P; Matos, PG; Oliveira, A;

Publication
CIRED - Open Access Proceedings Journal

Abstract

2019

Towards Intra-Datacentre High-Availability in CloudDBAppliance

Authors
Ferreira, L; Coelho, F; Alonso, AN; Pereira, J;

Publication
Proceedings of the 9th International Conference on Cloud Computing and Services Science

Abstract

2019

Recovery in CloudDBAppliance’s High-availability Middleware

Authors
Abreu, H; Ferreira, L; Coelho, F; Alonso, AN; Pereira, J;

Publication
Proceedings of the 8th International Conference on Data Science, Technology and Applications

Abstract

2020

A Comparison of Message Exchange Patterns in BFT Protocols: (Experience Report)

Authors
Silva, F; Alonso, AN; Pereira, J; Oliveira, R;

Publication
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Abstract
The performance and scalability of byzantine fault-tolerant (BFT) protocols for state machine replication (SMR) have recently come under scrutiny due to their application in the consensus mechanism of blockchain implementations. This led to a proliferation of proposals that provide different trade-offs that are not easily compared as, even if these are all based on message passing, multiple design and implementation factors besides the message exchange pattern differ between each of them. In this paper we focus on the impact of different combinations of cryptographic primitives and the message exchange pattern used to collect and disseminate votes, a key aspect for performance and scalability. By measuring this aspect in isolation and in a common framework, we characterise the design space and point out research directions for adaptive protocols that provide the best trade-off for each environment and workload combination. © IFIP International Federation for Information Processing 2020.

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