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Coarse indices for a tape-based data warehouse 用于基于磁带的数据仓库的粗索引
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655781
T. Johnson
Data warehouses allow users to make sense of large quantities of detail data. While most queries can be answered through summary data, some queries can only be answered by accessing the detail data. It is usually not cost-effective to store terabytes of detail data online; instead, the detail data is stored on tape. The problem we address in this paper is how to index tape-based detail data. Conventional indices on tens of terabytes of data can require terabytes of storage themselves. We propose the use of coarse indices for tape-based detail data. Instead of specifying all locations of a record containing a particular key, the coarse index specifies whether or not a region of tape contains at least one record with a particular key value. Our proposal is based on the observation that while long tape seeks are fast, short tape seeks are slow. Therefore, indices that point to the exact record location on tape do not provide performance benefits to justify the cost of their storage. A few bits pointing to an appropriate location are enough. In this paper, we present the design of such a coarse index, and provide fast algorithms for its updating and querying. Our experiments on a large data set taken from an existing data warehouse show that using compressed bitmap indices offer an order-of-magnitude reduction in index size, permitting the online storage of the coarse indices. Analytical and simulation models of the time to fetch selected records from tape show that using coarse indices almost always improves reduces the total loading time as compared to using dense tape-based indices or to using no index at all.
数据仓库允许用户理解大量的细节数据。虽然大多数查询都可以通过摘要数据来回答,但有些查询只能通过访问详细数据来回答。在线存储tb级的详细数据通常不划算;相反,详细数据存储在磁带上。我们在本文中解决的问题是如何索引基于磁带的详细数据。数十tb数据上的传统索引本身可能需要tb的存储空间。我们建议对基于磁带的详细数据使用粗索引。粗索引不是指定包含特定键的记录的所有位置,而是指定磁带的一个区域是否至少包含一条具有特定键值的记录。我们的建议是基于观察,而长磁带搜索速度快,短磁带搜索速度慢。因此,指向磁带上准确记录位置的索引不能提供性能优势来证明其存储成本的合理性。指向适当位置的几个位就足够了。本文给出了这种粗索引的设计,并提供了快速更新和查询的算法。我们对取自现有数据仓库的大型数据集进行的实验表明,使用压缩位图索引可以将索引大小减少一个数量级,从而允许对粗索引进行在线存储。从磁带中获取所选记录的时间的分析和模拟模型表明,与使用基于磁带的密集索引或根本不使用索引相比,使用粗索引几乎总是能缩短总加载时间。
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引用次数: 7
Cyclic allocation of two-dimensional data 二维数据循环分配
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655763
Sunil Prabhakar, K. Abdel-Ghaffar, D. Agrawal, A. E. Abbadi
Various proposals have been made for declustering 2D tiled data on multiple I/O devices. Strictly optimal solutions only exist under very restrictive conditions on the tiling of the 2D space or for very few I/O devices. In this paper, we explore allocation methods where no strictly optimal solution exists. We propose a general class of allocation methods, referred to as cyclic allocation methods, and show that many existing methods are instances of this class. As a result, various seemingly ad hoc and unrelated methods are presented in a single framework. Furthermore, the framework is used to develop new allocation methods that give better performance than any previous method and that approach the best feasible performance.
对于在多个I/O设备上分散2D平铺数据,已经提出了各种建议。严格的最优解决方案只存在于非常严格的条件下,即2D空间的平铺或非常少的I/O设备。本文讨论了不存在严格最优解的分配方法。我们提出了一类通用的分配方法,称为循环分配方法,并表明许多现有的方法是该类的实例。因此,在一个框架中呈现了各种看似特别的和不相关的方法。此外,该框架还用于开发新的分配方法,这些方法比以往任何方法都具有更好的性能,并且接近最佳可行性能。
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引用次数: 76
Dynamic granular locking approach to phantom protection in R-trees r树幻影保护的动态颗粒锁定方法
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655807
K. Chakrabarti, S. Mehrotra
Over the last decade (1988-98), the R tree has emerged as one of the most robust multidimensional access methods. However, before the R tree can be integrated as an access method to a commercial strength database management system, efficient techniques to provide transactional access to data via R trees need to be developed. Concurrent access to data through a multidimensional data structure introduces the problem of protecting ranges specified in the retrieval from phantom insertions and deletions (the phantom problem). Existing approaches to phantom protection in B trees (namely, key range locking) cannot be applied to multidimensional data structures since they rely on a total order over the key space on which the B tree is designed. The paper presents a dynamic granular locking approach to phantom protection in R trees. To the best of our knowledge, the paper provides the first solution to the phantom problem in multidimensional access methods based on granular locking.
在过去十年(1988- 1998)中,R树已成为最健壮的多维访问方法之一。然而,在将R树作为一种访问方法集成到商业强度的数据库管理系统之前,需要开发通过R树提供对数据的事务性访问的有效技术。通过多维数据结构对数据的并发访问引入了保护检索中指定的范围免受幽灵插入和删除的问题(幽灵问题)。B树中幻影保护的现有方法(即键范围锁定)不能应用于多维数据结构,因为它们依赖于B树设计所依据的键空间的总顺序。提出了一种动态颗粒锁定的R树幻像保护方法。就我们所知,本文首次提出了基于粒度锁的多维访问方法中幻像问题的解决方案。
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引用次数: 34
ECA rule support for distributed heterogeneous environments 对分布式异构环境的ECA规则支持
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655825
Sharma Chakravarthy, R. Le
The utility and functionality of active capability (event-condition-action or ECA rules) has been well established in the context of databases. Today, most of the commercial relational database management systems (RDBMSs) offer some form of ECA rule capability. In addition, there are several research prototypes that have extended the ECA rule capability to object-oriented database management systems (OODBMSs). Sentinel, developed at the University of Florida is one such prototype that supports an expressive composite event specification language (Snoop), efficient event detection (using generated wrappers), conditions and actions (as a combination of OQL and C++), multiple and cascaded rule processing (using a rule scheduler and nested transactions), a visualization tool, and an editor for dynamic creation and management of rules. In order for the active capability to be useful for a large class of advanced applications, it is necessary to go beyond what has been proposed/developed in the literature. Specifically, the extensions needed beyond the current state-of-the-art active capability are: (i) support active capability for non-database applications as well, (ii) support active capability for distributed environments; that is, allow ECA across applications, and (iii) support active capability for heterogeneous sources of events (whether they are databases or not). The authors address how they are planning on addressing some of the above extensions using a combination of existing components (COTS) and new functionality/services that are culled from their experience in designing and implementing Sentinel.
活动能力(事件-条件-操作或ECA规则)的效用和功能已经在数据库上下文中得到了很好的建立。如今,大多数商业关系数据库管理系统(rdbms)都提供了某种形式的ECA规则功能。此外,有几个研究原型已经将ECA规则功能扩展到面向对象的数据库管理系统(oodbms)。佛罗里达大学开发的Sentinel就是这样一个原型,它支持表达性的复合事件规范语言(Snoop)、高效的事件检测(使用生成的包装器)、条件和操作(作为OQL和c++的组合)、多规则和级联规则处理(使用规则调度器和嵌套事务)、可视化工具和用于动态创建和管理规则的编辑器。为了使主动能力对大量高级应用程序有用,有必要超越文献中提出/开发的内容。具体来说,除了当前最先进的活动能力之外,需要的扩展是:(i)支持非数据库应用程序的活动能力,(ii)支持分布式环境的活动能力;也就是说,允许跨应用程序的ECA,以及(iii)支持异构事件源的活动功能(无论它们是否是数据库)。作者阐述了他们是如何计划使用现有组件(COTS)和从他们设计和实现Sentinel的经验中挑选出来的新功能/服务的组合来解决上述一些扩展的。
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引用次数: 20
Ending the ROLAP/MOLAP debate: usage based aggregation and flexible HOLAP 结束关于ROLAP/MOLAP的争论:基于使用的聚合和灵活的HOLAP
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655775
C. Salka
Summary form only given, as follows. Over the past few years, OLAP vendors have engaged in a debate regarding relational versus multidimensional data stores. This debate has obscured the more significant problems facing today's OLAP customers: managing the exponential growth generated by multidimensional pre-aggregations, and architectural support for a wide array of OLAP data models. Microsoft discusses several aspects of its upcoming OLAP Server product, placing special emphasis on these areas. Solutions for managing voluminous pre-aggregates are discussed in the context of understanding of the dynamics of the data explosion problem, and a partial aggregation scheme that is adjusted according to user query needs. Flexible Hybrid OLAP is discussed as a compelling solution to a wide array of user needs and data requirements, with a focus on understanding the many different meanings associated with Hybrid OLAP and the strengths and weaknesses of each.
仅给出摘要形式,如下。在过去的几年中,OLAP供应商就关系数据存储与多维数据存储进行了争论。这场争论掩盖了当今OLAP客户面临的更重要的问题:管理由多维预聚合产生的指数级增长,以及对各种OLAP数据模型的体系结构支持。Microsoft讨论了其即将推出的OLAP Server产品的几个方面,特别强调了这些领域。在理解数据爆炸问题的动态和根据用户查询需求调整的部分聚合方案的背景下,讨论了管理大量预聚合的解决方案。本文将柔性混合OLAP作为一种引人注目的解决方案来讨论,以满足广泛的用户需求和数据需求,重点是理解与混合OLAP相关的许多不同含义以及每种含义的优缺点。
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引用次数: 6
Remote load-sensitive caching for multi-server database systems 用于多服务器数据库系统的远程负载敏感缓存
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655814
S. Venkataraman, J. Naughton, M. Livny
The recent dramatic improvements in the performance of commodity hardware has made clusters of workstations or PCs an attractive and economical platform upon which to build scalable database servers. These clusters have large aggregate memory capacities, however, since this global memory is distributed, good algorithms are necessary for memory management, or this large aggregate memory will go underutilized. The goal of the study is to develop and evaluate buffer management algorithms for database clusters. We propose a new buffer management algorithm, remote load sensitive caching (RLS caching), that uses novel techniques to combine data placement with a simple modification of standard client server page replacement algorithms to approximate a global LRU page replacement policy. Through an implementation in the SHORE database system, we evaluate the performance of RLS caching against other buffer management algorithms. Our study demonstrates that RLS caching indeed effectively manages the distributed memory of a server cluster.
最近商品硬件性能的显著改进使得工作站或pc集群成为一个有吸引力且经济的平台,可以在其上构建可扩展的数据库服务器。这些集群具有很大的聚合内存容量,但是,由于这个全局内存是分布式的,因此需要好的算法来进行内存管理,否则这个大的聚合内存将得不到充分利用。本研究的目标是开发和评估数据库集群的缓冲区管理算法。我们提出了一种新的缓冲区管理算法,远程负载敏感缓存(RLS缓存),它使用新颖的技术将数据放置与标准客户端服务器页面替换算法的简单修改相结合,以近似全局LRU页面替换策略。通过在SHORE数据库系统中的实现,我们评估了RLS缓存与其他缓冲区管理算法的性能。我们的研究表明,RLS缓存确实有效地管理了服务器集群的分布式内存。
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引用次数: 13
Design and performance of an assertional concurrency control system 一个断言并发控制系统的设计与性能
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655806
A. Bernstein, D. S. Gerstl, Wai-Hong Leung, P. M. Lewis
Serializability has been widely accepted as the correctness criterion for databases subject to concurrent access. Serializable execution is generally implemented using a two phase locking algorithm that locks items in the database to delay transactions that care in danger of performing in a nonserializable fashion. Such delays are unacceptable in high performance database systems and in systems supporting long running transactions. A number of models have been proposed in which transactions are decomposed into smaller, atomic, interleavable steps. A shortcoming of much of this work is that little guidance is provided as to how transactions should be decomposed and what interleavings preserve correct execution. We previously proposed a new correctness criterion, weaker than serializability, that guarantees that each transaction satisfies its specification (A. Bernstein and P. Lewis, 1996). Based on that correctness criterion, we have designed and implemented a new concurrency control. Experiments using the new concurrency control demonstrate significant improvement in performance when lock contention is high.
可序列化性已被广泛接受为并发访问数据库的正确性标准。可序列化执行通常使用两阶段锁定算法实现,该算法锁定数据库中的项,以延迟可能以不可序列化方式执行的事务。这种延迟在高性能数据库系统和支持长时间运行事务的系统中是不可接受的。已经提出了许多模型,在这些模型中,事务被分解为更小的、原子的、可交叉的步骤。大部分工作的一个缺点是,对于如何分解事务以及怎样的交织保持正确的执行,几乎没有提供指导。我们之前提出了一个新的正确性标准,比序列化性弱,它保证每个事务满足其规范(a . Bernstein和P. Lewis, 1996)。基于这个正确性标准,我们设计并实现了一个新的并发控制。使用新并发控制的实验表明,在锁争用高的情况下,性能有了显著提高。
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引用次数: 12
SEMCOG: a hybrid object-based image database system and its modeling, language, and query processing SEMCOG:一个基于对象的混合图像数据库系统及其建模、语言和查询处理
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655788
Wen-Syan Li, K. Candan
Image data is structurally more complex than traditional types of data. An image can be viewed as a compound object containing many sub-objects. Each sub-object corresponds to image regions that are visually and semantically meaningful (e.g. car, man, etc.). We introduce a hierarchical structure for image modeling that supports image retrieval, at both the whole-image and object levels, using combinations of semantic expressions and visual examples. We introduce an image database system called SEMCOG (SEMantics and COGnition-based image retrieval). SEMCOG aims at integrating semantics- and cognition-based approaches and allows queries based on object-level information. We present a formal definition of a multimedia query language, we give details of the database's implementation and query processing, and we discuss our methods for merging similarities from different types of query criteria.
图像数据在结构上比传统类型的数据更为复杂。图像可以看作是包含许多子对象的复合对象。每个子对象对应于视觉上和语义上有意义的图像区域(例如,汽车,人等)。我们引入了一个层次结构的图像建模,支持图像检索,在整个图像和对象级别,使用语义表达和视觉示例的组合。介绍了一种基于语义和认知的图像检索系统SEMCOG。SEMCOG旨在集成基于语义和基于认知的方法,并允许基于对象级信息的查询。我们给出了多媒体查询语言的正式定义,给出了数据库实现和查询处理的细节,并讨论了从不同类型的查询标准中合并相似性的方法。
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引用次数: 15
Grouping techniques for update propagation in intermittently connected databases 间歇连接数据库中更新传播的分组技术
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655756
Sameer Mahajan, M. Donahoo, S. Navathe, M. Ammar, Sanjoy Malik
We consider an environment where one or more servers carry databases that are of interest to a community of clients. The clients are only intermittently connected to the server for brief periods of time. Clients carry a part of the database for their own processing and accumulate local updates while disconnected. We call this the Intermittently Connected Database (ICDB) environment. ICDBs have a wide variety of applications including sales force automation, insurance claim processing, and mobile workforces. Our focus is on the problem of update propagation at the server in ICDBs and the associated processing at the clients. The typical client-centric approach involves the communication and processing of updates and transactions on a per-client basis, ignoring the overlap of data between clients. The complexity of this approach is in the order of the number of connecting clients, thereby limiting the scalability of the server. We propose a data-centric approach which clusters data into groups and assigns to each client one or more of these groups. The proposed scheme results in server processing complexity on the order of the number of groups, which we control. We propose various techniques for grouping and discuss the processing required at the clients to enable the grouping approach. While the client-centric approach is expected to significantly degrade with the increasing number of clients, we expect that a properly designed grouping scheme will sustain a number of clients that is significantly larger. A prototype has been developed and performance studies are in progress.
我们考虑一个环境,其中一个或多个服务器携带客户端社区感兴趣的数据库。客户端只是在很短的时间内间歇性地连接到服务器。客户端携带数据库的一部分用于自己的处理,并在断开连接时积累本地更新。我们称之为间歇连接数据库(ICDB)环境。icdb具有各种各样的应用程序,包括销售人员自动化、保险索赔处理和移动工作人员。我们的重点是在icdb中的服务器上的更新传播问题以及在客户机上的相关处理。典型的以客户端为中心的方法涉及在每个客户端基础上通信和处理更新和事务,忽略了客户端之间的数据重叠。这种方法的复杂性按照连接客户机数量的顺序排列,从而限制了服务器的可伸缩性。我们提出了一种以数据为中心的方法,将数据分组,并将其中一个或多个分组分配给每个客户端。所提出的方案导致服务器处理复杂度按我们所控制的组数的顺序排列。我们提出了各种分组技术,并讨论了在客户端启用分组方法所需的处理。虽然以客户为中心的方法可能会随着客户端数量的增加而显著降低性能,但我们希望设计得当的分组方案能够支持数量显著增加的客户端。一个原型已经开发出来,性能研究正在进行中。
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引用次数: 28
Content-based multimedia information management 基于内容的多媒体信息管理
Pub Date : 1998-02-23 DOI: 10.1109/ICDE.1998.655783
R. Jain
Summary form only given. All image search engines provide mechanisms to search based on keywords and provide the ability to do content-based searching using querying by pictorial example. In this paper, first we present some results from current image databases. Then we present a new approach to exploring image databases. Most of our current results are drawn from image and video asset management systems designed at Virage. The new approach is based on a navigational paradigm being developed at the University of California, San Diego.
只提供摘要形式。所有图像搜索引擎都提供了基于关键字的搜索机制,并通过图形示例提供了使用查询进行基于内容的搜索的能力。在本文中,我们首先给出了一些来自现有图像数据库的结果。然后,我们提出了一种新的图像数据库探索方法。我们目前的大部分结果都来自于Virage设计的图像和视频资产管理系统。这种新方法是基于加州大学圣地亚哥分校正在开发的导航范式。
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引用次数: 15
期刊
Proceedings 14th International Conference on Data Engineering
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