Browsing by Subject "Distributed database systems"

Now showing 1 - 5 of 5

Open Access
Data replication versus timing constraints in distributed database systems
(ACM, 1994-03) Ulusoy, Özgür
In a database system supporting a real-time application, each transaction is associated with a timing constraint, typically in the form of a deadline. Replicated database systems possess desirable features for real-time applications, such as a high level of data availability, and potentially improved response time for queries. On the other hand, multiple copy updates lead to a considerable overhead due to the communication required among the data sites holding the copies. In this paper, we investigate the impact of storing multiple copies of data on satisfying the timing constraints of real-time transactions. A detailed performance model of a distributed database system is employed in evaluating the effects of various workload parameters and design alternatives on the system performance. The performance is expressed in terms of the fraction of satisfied transaction deadlines.
Open Access
Distributed block formation and layout for disk-based management of large-scale graphs
(Springer, 2017) Yaşar, A.; Gedik, B.; Ferhatosmanoğlu, H.
We are witnessing an enormous growth in social networks as well as in the volume of data generated by them. An important portion of this data is in the form of graphs. In recent years, several graph processing and management systems emerged to handle large-scale graphs. The primary goal of these systems is to run graph algorithms and queries in an efficient and scalable manner. Unlike relational data, graphs are semi-structured in nature. Thus, storing and accessing graph data using secondary storage requires new solutions that can provide locality of access for graph processing workloads. In this work, we propose a scalable block formation and layout technique for graphs, which aims at reducing the I/O cost of disk-based graph processing algorithms. To achieve this, we designed a scalable MapReduce-style method called ICBL, which can divide the graph into a series of disk blocks that contain sub-graphs with high locality. Furthermore, ICBL can order the resulting blocks on disk to further reduce non-local accesses. We experimentally evaluated ICBL to showcase its scalability, layout quality, as well as the effectiveness of automatic parameter tuning for ICBL. We deployed the graph layouts generated by ICBL on the Neo4j open source graph database, http://www.neo4j.org/ (2015) graph database management system. Our results show that the layout generated by ICBL reduces the query running times over Neo4j more than 2 × compared to the default layout. © 2017, Springer Science+Business Media New York.
Open Access
PetaShare: A reliable, efficient and transparent distributed storage management system
(2011) Kosar, T.; Akturk I.; Balman, M.; Wang X.
Modern collaborative science has placed increasing burden on data management infrastructure to handle the increasingly large data archives generated. Beside functionality, reliability and availability are also key factors in delivering a data management system that can efficiently and effectively meet the challenges posed and compounded by the unbounded increase in the size of data generated by scientific applications. We have developed a reliable and efficient distributed data storage system, PetaShare, which spans multiple institutions across the state of Louisiana. At the back-end, PetaShare provides a unified name space and efficient data movement across geographically distributed storage sites. At the front-end, it provides light-weight clients the enable easy, transparent and scalable access. In PetaShare, we have designed and implemented an asynchronously replicated multi-master metadata system for enhanced reliability and availability, and an advanced buffering system for improved data transfer performance. In this paper, we present the details of our design and implementation, show performance results, and describe our experience in developing a reliable and efficient distributed data management system for data-intensive science. © 2011 - IOS Press and the authors. All rights reserved.
Open Access
Processing real-time transactions in a replicated database system
(Springer/Kluwer Academic Publishers, 1994) Ulusoy, Özgür
A database system supporting a real-time application has to provide real-time information to the executing transactions. Each real-time transaction is associated with a timing constraint, typically in the form of a deadline. It is difficult to satisfy all timing constraints due to the consistency requirements of the underlying database. In scheduling the transactions it is aimed to process as many transactions as possible within their deadlines. Replicated database systems possess desirable features for real-time applications, such as a high level of data availability, and potentially improved response time for queries. On the other hand, multiple copy updates lead to a considerable overhead due to the communication required among the data sites holding the copies. In this paper, we investigate the impact of storing multiple copies of data on satisfying the timing constraints of real-time transactions. A detailed performance model of a distributed database system is employed in evaluating the effects of various workload parameters and design alternatives on the system performance. The performance is expressed in terms of the fraction of satisfied transaction deadlines. A comparison of several real-time concurrency control protocols, which are based on different approaches in involving timing constraints of transactions in scheduling, is also provided in performance experiments. © 1994 Kluwer Academic Publishers.
Open Access
Understanding the tendency of software development teams to develop software over the cloud
(CEUR-WS, 2016) Çoban, S.; Uçar, Erkan; Chouseinoglou, Oumout; Sevgi, C.; Testik, Murat Caner
Today, Cloud Computing offers attractive and effective solutions for organizations which enable them to decrease IT costs, provide flexibility to ser-vices and make it easier to access IT services -Therefore enable faster market entries. For an organization that decides to make use of Cloud services, there are various factors to evaluate - similar to outsourcing. In this paper, we studied these factors through the literature and then we tried to understand the viewpoints of software developers regarding the existing and possible future usage of Cloud in software development processes. In this context, we prepared a questionnaire based on the findings in the literature and applied it to software development team members working in technoparks in Turkey. We used the dataset which is obtained from this questionnaire to observe the relationship between the tendency of using Cloud in software development processes and the factors effecting them. This research is performed as the first phase of a study with a larger scope, de-signed to forecast the Cloud needs of software developing organizations and it provides important findings. The questionnaire findings also describe the current demographics of software development organizations in Turkish technoparks to-gether with their perception of Cloud services.