The Experts below are selected from a list of 2040 Experts worldwide ranked by ideXlab platform
Seokil Song - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Partition lock method to reduce transaction abort rates of cloud database
Cluster Computing, 2015Co-Authors: T. Kim, Seokil SongAbstract:Generally, existing cloud data management systems (CDMSs) support Partition Tolerance in mandatory and sacrifice consistency according to the CAP theory. Partition Tolerance means that the database can be split over multiple servers to guarantee consistency or availability, even though the network is Partitioned. This property is mandatory in CDMSs which consist of multiple servers. On the contrary, consistency of database is not strongly required in applications of CDMSs such as online shopping, search engine and so on. However, recently emerging applications such as online gaming, collaborative editing, and social networking require strong consistency, which requires that there be only one copy of each data item, and that only serializable access be permitted. Several approaches have been proposed to support consistency in CDMSs. These can be classified into three groups. In the first group of approaches, transactions are processed over multiple records in only one node. In the second group, limited wider transaction support is given to allow transactions to run in multiple nodes with some constraints. In the third group, transaction services are unbundled from the kernel of database management systems. In this paper, we propose a transaction processing method for CDMSs in which snapshot isolation (SI) techniques are applied to the unbundling transaction approach to increase its transaction throughput. The Partition locking used by the unbundling transaction approach is static, and therefore, the number of Partitions does not change, even when the number of records or the access frequency increases. This feature of the approach may increase the number of failed transactions when a SI technique is applied to the approach. We propose a dynamic Partitioning lock method to solve these problems. Our proposed method monitors the number of transactions that access each Partition and the number of records in each Partition. Then, it splits any Partition that is accessed more times than a particular threshold and maintains the split information using a KD-tree. The results of simulations conducted using our proposed dynamic Partitioning lock methods show that less transaction aborts occur with our proposed method than with conventional methods.
Songseokil - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Partition lock method to reduce transaction abort rates of cloud database
Cluster Computing, 2015Co-Authors: Kimtaehwan, SongseokilAbstract:Generally, existing cloud data management systems (CDMSs) support Partition Tolerance in mandatory and sacrifice consistency according to the CAP theory. Partition Tolerance means that the database...
T. Kim - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Partition lock method to reduce transaction abort rates of cloud database
Cluster Computing, 2015Co-Authors: T. Kim, Seokil SongAbstract:Generally, existing cloud data management systems (CDMSs) support Partition Tolerance in mandatory and sacrifice consistency according to the CAP theory. Partition Tolerance means that the database can be split over multiple servers to guarantee consistency or availability, even though the network is Partitioned. This property is mandatory in CDMSs which consist of multiple servers. On the contrary, consistency of database is not strongly required in applications of CDMSs such as online shopping, search engine and so on. However, recently emerging applications such as online gaming, collaborative editing, and social networking require strong consistency, which requires that there be only one copy of each data item, and that only serializable access be permitted. Several approaches have been proposed to support consistency in CDMSs. These can be classified into three groups. In the first group of approaches, transactions are processed over multiple records in only one node. In the second group, limited wider transaction support is given to allow transactions to run in multiple nodes with some constraints. In the third group, transaction services are unbundled from the kernel of database management systems. In this paper, we propose a transaction processing method for CDMSs in which snapshot isolation (SI) techniques are applied to the unbundling transaction approach to increase its transaction throughput. The Partition locking used by the unbundling transaction approach is static, and therefore, the number of Partitions does not change, even when the number of records or the access frequency increases. This feature of the approach may increase the number of failed transactions when a SI technique is applied to the approach. We propose a dynamic Partitioning lock method to solve these problems. Our proposed method monitors the number of transactions that access each Partition and the number of records in each Partition. Then, it splits any Partition that is accessed more times than a particular threshold and maintains the split information using a KD-tree. The results of simulations conducted using our proposed dynamic Partitioning lock methods show that less transaction aborts occur with our proposed method than with conventional methods.
Hernán Melgratti - One of the best experts on this subject based on the ideXlab platform.
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On the behaviour of general purpose applications on cloud storages
Service Oriented Computing and Applications, 2015Co-Authors: Laura Bocchi, Hernán MelgrattiAbstract:Managing data over cloud infrastructures raises novel challenges with respect to existing and well-studied approaches such as ACID and long-running transactions. One of the main requirements is to provide availability and Partition Tolerance in a scenario with replicas and distributed control. This comes at the price of a weaker consistency, usually called eventual consistency. These weak memory models have proved to be suitable in a number of scenarios, such as the analysis of large data with map reduce. However, due to the widespread availability of cloud infrastructures, weak storages are used not only by specialised applications but also by general purpose applications. We provide a formal approach, based on process calculi, to reason about the behaviour of programs that rely on cloud stores. For instance, it allows to check that the composition of a process with a cloud store ensures ‘strong’ properties through a wise usage of asynchronous message-passing; in this case, we say that the process supports the consistency level provided by the cloud store. The proposed approach is compositional: the support of a consistency level is preserved by parallel composition when the preorder used to compare process-store ensembles is the weak simulation.
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WS-FM - On the Behaviour of General-Purpose Applications on Cloud Storages
Lecture Notes in Computer Science, 2014Co-Authors: Laura Bocchi, Hernán MelgrattiAbstract:Managing data over cloud infrastructures raises novel challenges with respect to existing and well studied approaches such as ACID and long running transactions. One of the main requirements is to provide availability and Partition Tolerance in a scenario with replicas and distributed control. This comes at the price of a weaker consistency, usually called eventual consistency. These weak memory models have proved to be suitable in a number of scenarios, such as the analysis of large data with Map-Reduce. However, due to the widespread availability of cloud infrastructures, weak storages are used not only by specialised applications but also by general purpose applications. We provide a formal approach, based on process calculi, to reason about the behaviour of programs that rely on cloud stores. For instance, one can check that the composition of a process with a cloud store ensures ‘strong’ properties through a wise usage of asynchronous message-passing.
Sudipto Das - One of the best experts on this subject based on the ideXlab platform.
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COMAD - Rethinking eventual consistency: can we do better?
2013Co-Authors: Sudipto DasAbstract:Today's data-driven internet-facing applications pose unprecedented challenges to the database systems that back these application. In addition to the immense scale of data, thousands of concurrent requests, and low latency response, these applications also strive for 24X7 availability. The big data serving systems empowering these applications must therefore have low request latencies, be highly-available, and be geo-replicated. As a result, there has been a resurgence of work on replicated, distributed database systems to meet the demands of intermittently-connected clients and of disaster-tolerant databases that span data centers spanning the globe. Many of these data serving systems weaken the criteria for replica-consistency or isolation, and in some cases add new mechanisms, to improve Partition-Tolerance, availability, and performance. In this talk, I'll present a framework for comparing these criteria and mechanisms, to help architects navigate through this complex design space and reason about the various weak forms of replica consistency. Joint work with Philip A. Bernstein.
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SIGMOD Conference - Rethinking eventual consistency
Proceedings of the 2013 international conference on Management of data - SIGMOD '13, 2013Co-Authors: Philip A. Bernstein, Sudipto DasAbstract:There has been a resurgence of work on replicated, distributed database systems to meet the demands of intermittently-connected clients and of disaster-tolerant databases that span data centers. Many systems weaken the criteria for replica-consistency or isolation, and in some cases add new mechanisms, to improve Partition-Tolerance, availability, and performance. We present a framework for comparing these criteria and mechanisms, to help architects navigate through this complex design space.