Mobile Databases: a Selection of Open Issues and Research Directions

International audienceThis paper reports on the main results of a specific action on mobile databases conducted by CNRS in France from October 2001 to December 2002. The objective of this action was to review the state of progress in mobile databases and identify major research directions for the French database community. Rather than provide a survey of all important issues in mobile databases, this paper gives an outline of the directions in which the action participants are now engaged, namely: copy synchronization in disconnected computing, mobile transactions, database embedded in ultra-light devices, data confidentiality, P2P dissemination models and middleware adaptability

SGBD embarqué dans une puce : retour d'expérience

National audienceLa carte à puce est aujourd'hui l'objet portable sécurisé le plus répandu. Il y a 4 ans, nous avons jeté les bases d'une étude portant sur l'embarquement de techniques bases de données dans une carte à puce. Cette étude a conduit à la définition de principes de conception pour ce que nous avons appelé alors PicoDBMS, un système de gestion de bases de données (SGBD) complet intégré dans une carte à puce. Depuis, grâce au progrès du matériel et aux efforts conjoints de notre équipe et de notre partenaire industriel, les principes définis initialement ont donné naissance à un prototype complet tournant sur une plate-forme carte à puce expérimentale. Cet article reconsidère la formulation du problème initial à la lumière des évolutions matérielles et applicatives. Il introduit ensuite un banc d'essai dédié aux bases de données embarquées dans des puces et présente une analyse de performance détaillée de notre prototype. Enfin, il dresse des perspectives de recherche dans le domaine de la gestion de données dans les puces sécurisées

Smart Card DBMS: where are we now?

Smart card is today the most widespread secured portable computing device. Four years ago, we addressed the problem of scaling down database techniques for the smart card and we proposed the design of what we called a PicoDBMS, a full-fledged database system embedded in a smart card. Since then, thanks to the hardware progress and to the joint implementation efforts of our team and our industrial partner, this utopian design gave birth to a complete prototype running on an experimental smart card platform. This paper revisits the problem statement in the light of the hardware and applications evolution. Then, it introduces a benchmark dedicated to Pico–style databases and provides an extensive performance analysis of our prototype, discussing lessons learned at experimentation time and helping selecting the appropriate storage and indexation model for a given class of embedded applications. Finally, it draws new research perspectives for data management on secured chips (smart cards, USB dongles, multimedia rendering devices, smart objects in an ambient intelligence surrounding)

Effective Use of SSDs in Database Systems

With the advent of solid state drives (SSDs), the storage industry has experienced a revolutionary improvement in I/O performance. Compared to traditional hard disk drives (HDDs), SSDs benefit from shorter I/O latency, better power efficiency, and cheaper random I/Os. Because of these superior properties, SSDs are gradually replacing HDDs. For decades, database management systems have been designed, architected, and optimized based on the performance characteristics of HDDs. In order to utilize the superior performance of SSDs, new methods should be developed, some database components should be redesigned, and architectural decisions should be revisited. In this thesis, novel methods are proposed to exploit the new capabilities of modern SSDs to improve the performance of database systems. The first is a new method for using SSDs as a fully persistent second level memory buffer pool. This method uses SSDs as a supplementary storage device to improve transactional throughput and to reduce the checkpoint and recovery times. A prototype of the proposed method is compared with its closest existing competitor. The second considers the impact of the parallel I/O capability of modern SSDs on the database query optimizer. It is shown that a query optimizer that is unaware of the parallel I/O capability of SSDs can make significantly sub-optimal decisions. In addition, a practical method for making the query optimizer parallel-I/O-aware is introduced and evaluated empirically. The third technique is an SSD-friendly external merge sort. This sorting technique has better performance than other common external sorting techniques. It also improves the SSD's lifespan by reducing the number of write operations required during sorting