Soror Sahri

An overview of a scalable distributed database system SD-SQL server

We present a scalable distributed database system called SD-SQL Server. Its original feature is dynamic and transparent repartitioning of growing tables, avoiding the cumbersome manual repartitioning that characterize current technology. SD-SQL Server re-partitions a table when an insert overflows existing segments. With the comfort of a single node SQL Server user, the SD-SQL Server user has larger tables or gets a faster response time through the dynamic parallelism. We present the architecture of our system, its implementation and the performance analysis. We show that the overhead of our scalable table management should be typically negligible.

DBaaS-Expert: A Recommender for the Selection of the Right Cloud Database

The most important benefit of Cloud Computing is that organizations no longer need to expend capital up-front for hardware and software purchases. Indeed, all services are provided on a pay-per-use basis. The cloud services market is forecast to grow, and numerous providers offer database as a service (DBaaS). Nevertheless, as the number of DBaaS’ offerings increases, it becomes difficult to compare various offerings through checking of a documentation ads-oriented. In this paper, we propose and describe DBaaS-Expert – a framework which helps a user to choose the right DBaaS Cloud Provider among DBaaS’ offerings. The core components of DBaaS-Expert is first an ontology which captures cloud data management systems services concepts, and second a ranking core which scores each DBaaS offer in terms of criteria.

Quality-Based Online Data Reconciliation

One of the main challenges in data matching and data cleaning, in highly integrated systems, is duplicates detection. While the literature abounds of approaches detecting duplicates corresponding to the same real-world entity, most of these approaches tend to eliminate duplicates (wrong information) from the sources, hence leading to what is called data repair. In this article, we propose a framework that automatically detects duplicates at query time and effectively identifies the consistent version of the data, while keeping inconsistent data in the sources. Our framework uses matching dependencies (MDs) to detect duplicates through the concept of data reconciliation rules (DRR) and conditional function dependencies (CFDs) to assess the quality of different attribute values. We also build a duplicate reconciliation index (DRI), based on clusters of duplicates detected by a set of DRRs to speed up the online data reconciliation process. Our experiments of a real-world data collection show the efficiency and effectiveness of our framework.

Be a Collaborator and a Competitor in Crowdsourcing System

Crowd sourcing is emerging as a powerful paradigm to solve a wide range of tedious and complex problems in various enterprise applications. It spawns the issue of finding the unknown collaborative and competitive group of solvers. The formation of collaborative team should provide the best solution and treat that solution as a trade secret avoiding data leak between competitive teams due to reward behind the outsourcing of the issue. The formation of effective competitive teams not only requires adequate skills between members of each team, but also good team connectivity through social network and to provide the best solution and treat that solution as a trade secret avoiding data leak between teams due to reward behind the outsourcing of the issue. In this paper, we propose a data leak aware crowd sourcing system called Social Crowd. We introduce a clustering algorithm that uses social relationships between crowd workers to discover all possible teams while avoiding inter-team data leakage.

TIMED PRIVACY-AWARE BUSINESS PROTOCOLS

Web services privacy issues have been attracting more and more attention in the past years. Since the number of Web services-based business applications is increasing, the demands for privacy enhancing technologies for Web services will also be increasing in the future. In this paper, we investigate an extension of business protocols, i.e. the specification of which message exchange sequences are supported by the web service, in order to accommodate privacy aspects and time-related properties. For this purpose we introduce the notion of Timed Privacy-aware Business Protocols (TPBPs). We also discuss TPBP properties can be checked and we describe their verification process.

Scalable web services interface for SD-SQL server

SD-SQL Server is a scalable distributed database system. Its original feature is dynamic and transparent repartitioning of growing tables. It avoids the cumbersome manual repartitioning necessary with current technology. SD-SQL Server re-partitions a (distributed) table when an insert overflows existing segments. To its user, SD_SQL offers the comfort of a single node, while allowing the larger tables and faster response time made possible by dynamic parallelism. We present the architecture of our system and its command interface. We present the Extended Web Services (EWS) Interface we have recently added to SD-SQL Server. We study the relative EWS query speed. It remains insufficient for larger data sets to be retrieved.

Summary-Based Pattern Tableaux Generation for Conditional Functional Dependencies in Distributed Data

Conditional Functional Dependencies (CFD) are an extension of Functional Dependencies (FDs) that capture rules about the data consistency. Existing work on discovering CFDs focused on centralized data. Here, we extend this work to horizontally distributed relations. Given an embedded functional dependency, we generate a pattern tableau that represents a CFD. The original feature of our work is generating CFD pattern tableaux from a distributed relation, without merging all the distributed tuples in a centralized relation. We propose a distributed algorithm based on the concept of pattern summary that minimizes data shipping between the sites of distributed relation.

Design Issues of Shingled Write Disk for Database

To maintain the continuing growth of bit density in magnetic recording media, the disk industry will have to change technologies. Shingled write disks are expected to be the next generation of high capacity magnetic disks and alreadyin prototype. Shingled write technology is not disruptive at the level of disk design and manufacturing, but as shingled writes prevent updates in place, the technology is disruptive at the level of usage. It is possible to design a disk device driver or disk firmware that allows a shingled write disk to be used as a drop in replacement for traditional disks. Database implementations however have traditionally bypassed the file system and accessed the disk directly in order to achieve better performance. We discuss here adaptation of B+-trees and linear hash tables to shingled write disk to support indexed database tables and secondary indices. Our proposal is based on dividing the disk in low-capacity Random Access Zones (RAZ) and high capacity Log Access Zones (LAZ). The LAZ use the shingled disk effectively while RAZ places guard bands around each track in the zone in order to regain the capacity of in-place updates at the costs of loosing capacity.