Cookies
Usamos cookies para melhorar nosso site e a sua experiência. Ao continuar a navegar no site, você aceita a nossa política de cookies. Ver mais
Fechar
  • Menu
Sobre

Sobre

Colaborei no projecto Europeu GORDA, cujo objectivo era fomentar a utilização de replicação de base de dado como forma de resolver os desafios encontrados nos sistemas de base de dados actuais. O meu trabalho foi de dotar o projecto com uma consola gráfica de monitorização e gestão utilizando JMX.

Também estive envolvida no projecto P-SON, em particular no desenvolvimento de aplicações para o protocolo de disseminação epidémica NeEM. Neste contexto, trabalhei numa arquitectura de caching e disseminação de feeds RSS que utiliza redes P2P para este fim e, posteriormente, numa arquitectura genérica content-push baseada em feeds Web e serviços e redes sociais, no qual se baseou a minha dissertação de Mestrado. Também trabalhei num protocolo e disseminação epidémica que tira partido dos interesses partilhados dos participantes sem chegar a revelá-los.

No contexto do meu Doutoramento, o meu trabalho focou-se na forma de aproximar as aplicações tradicionais centradas numa base de dados e as promessas de alta disponibilidade.

Actualmente, faço parte do projecto europeu CloudDBAppliance e tenho estado, também, a colaborar com o CPES no contexto dos projectos europeus UPGRID e InteGrid.

Tópicos
de interesse
Detalhes

Detalhes

  • Nome

    Ana Nunes Alonso
  • Cluster

    Informática
  • Cargo

    Investigador
  • Desde

    01 fevereiro 2012
003
Publicações

2017

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

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

Publicação
CIRED - Open Access Proceedings Journal

Abstract

2013

Improving transaction abort rates without compromising throughput through judicious scheduling

Autores
Nunes, A; Pereira, J;

Publicação
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

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

Publicação
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.