Although the distributed database systems has been studyed for a long time there has been only few commercial systems available. The main reason for this is that the distributed commit processing costs too much which ...
详细信息
This model of communication is using database replication and simple database abstraction models for transmitting data from a web hosting backend to its web hosting dedicated client servers assuring an asynchronous da...
详细信息
Advancements in communication technologies have given rise to Mobile databasesystems (MDS). MDS allows a mobile user to initiate transactions from anywhere and at any time and guarantees their consistency preserving ...
详细信息
ISBN:
(纸本)9781605588124
Advancements in communication technologies have given rise to Mobile databasesystems (MDS). MDS allows a mobile user to initiate transactions from anywhere and at any time and guarantees their consistency preserving execution. Transaction processing in MDS has been suggested by modifying the traditional two and three phase commit (2PC) to accommodate the limitations of a Mobile Host and wireless network like intermitted connectivity, limited power, limited memory etc. A timeout based approach "Transaction Commit on Timeout", TCOT, has been suggested which shows better performance compared to 2PC and 3PC. However, this scheme does not explicitly consider a distributeddatabase system. We propose a scheme distributed Transaction Commit on Timeout, DTCOT, to commit the transaction in a MDS environment with distributeddatabase. This scheme uses a timeout to decide a commit or abort. DTCOT requires two coordinators: - one for coordinating the entire transaction execution and one, which acts as the interface to the distributeddatabase (i.e. database coordinator). The database coordinator is required because data distribution must be transparent the end user (i.e. transaction coordinator). This is a one-phase protocol due to which the time and message complexity are much lower compared to the conventional 2 phases commit and 3 phase commit protocols. We will compare the performance with the modified 2PC and show that it performs better w.r.t. Message and time complexity. Copyright 2010 ACM.
In many distributed real-time systems, certain critical data need to be replicated to achieve fault-tolerance and improved performance. Schedulers for such distributed real-time systems must satisfy timing constraints...
详细信息
In many distributed real-time systems, certain critical data need to be replicated to achieve fault-tolerance and improved performance. Schedulers for such distributed real-time systems must satisfy timing constraints of transactions and preserve data consistency. In this paper we presents a replication control algorithm, which integrates real-time scheduling and replication control to achieve the desired level of fault-tolerance. The algorithm adopts a majority consensus scheme for replication control and employs epsilon-serializability, a correctness criterion which is less stringent than conventional one-copy serializability. The performance of the algorithm is compared with that of a real-time token-based algorithm.
As more data management software is designed for deployment in public and private clouds, or on a cluster of commodity servers, new distributed storage systems increasingly achieve high data access throughput via part...
详细信息
As more data management software is designed for deployment in public and private clouds, or on a cluster of commodity servers, new distributed storage systems increasingly achieve high data access throughput via partitioning and replication. In order to achieve high scalability, however, today's systems generally reduce transactional support, disallowing single transactions from spanning multiple partitions. This article describes Calvin, a practical transaction scheduling and data replication layer that uses a deterministic ordering guarantee to significantly reduce the normally prohibitive contention costs associated with distributed transactions. This allows near-linear scalability on a cluster of commodity machines, without eliminating traditional transactional guarantees, introducing a single point of failure, or requiring application developers to reason about data partitioning. By replicating transaction inputs instead of transactional actions, Calvin is able to support multiple consistency levels-including Paxos-based strong consistency across geographically distant replicas-at no cost to transactional throughput. Furthermore, Calvin introduces a set of tools that will allow application developers to gain the full performance benefit of Calvin's server-side transaction scheduling mechanisms without introducing the additional code complexity and inconvenience normally associated with using DBMS stored procedures in place of ad hoc client-side transactions.
After a rough characterization of BAPAS-DB its usage in two distributed computer control systems at Daimler-Benz and the Hospital Großhadern, Munich, is described. Special attention is given to the call interface...
详细信息
After a rough characterization of BAPAS-DB its usage in two distributed computer control systems at Daimler-Benz and the Hospital Großhadern, Munich, is described. Special attention is given to the call interface DBV of BAPAS-DB, which allows to use BAPAS-DB as distributeddatabase system.
Building on prior work on distributeddatabases and the CALM Theorem, we define and study the question of free termination: in the absence of distributed coordination, what query properties allow nodes in a distribute...
详细信息
The variety of user interfaces of existing database querying tools made the interfaces unfriendly to the database users. The users are forced to shift between different application environments to pass information bet...
详细信息
The variety of user interfaces of existing database querying tools made the interfaces unfriendly to the database users. The users are forced to shift between different application environments to pass information between applications. The diverse interface definitions and command sets of the different applications prevent the users from having high productivity. In this paper we propose a new standard querying interface, whose querying power is distributed to applications throughout the operating system. The proposed querying interface would improve the data accessibility of the databases. This new standard is called distributed Querying Interface Standard(DQIS) by the authors.
distributeddatabase theory for a single view of a distributeddatabase consisting of homogeneous relational databases has been known for over a decade. The application of some of this theory in commercial products ha...
详细信息
distributeddatabase theory for a single view of a distributeddatabase consisting of homogeneous relational databases has been known for over a decade. The application of some of this theory in commercial products has not been established. Although some commercial distributeddatabase products support naming and location transparency, these products do not provide full support for fragmentation transparency. Providing support for declaring and reasoning about fragments requires adding data definition capabilities and updating complex query optimizers. This article presents a syntax for the specification of fragmentation and describes a prototype for reasoning about the fragmentation criteria. This prototype examines the feasibility of not having to update the existing query optimizer by taking a distributed SQL query and fragmentation specification and generating a sequence of SQL queries expressed over the fragments, which is then input to the established query optimizer. This article provides a case study of this approach on a commercial distributeddatabase product. A benchmark for distributeddatabases for decision support, known as (DS)-S-3, is introduced and used in the case study. The study shows that a two-step process of first optimizing with respect to the fragmentation criteria, followed by the existing distributed query optimization, results in performant query evaluation plans. (C) 1996 by Elsevier Science Inc.
Building on prior work on distributeddatabases and the CALM Theorem, we define and study the question of free termination: in the absence of distributed coordination, what query properties allow nodes in a distribute...
详细信息
暂无评论