Database System

Distinct software metrics have been proposed for programs. By contrast, metrics for databases have been neglected on the grounds that databases were mere plain files that do not affect considerably information systems maintainability. However, later enhancements on database systems ...

Abstract With the increasing popularity of object-relational technology, it is becoming important to have a methodology which allows designers to exploit the great modelling power of object-oriented conceptual models (OOCMs) and yet which still facilitates ...

Real-time database systems incorporate the notion of a deadline into the database system model. USU-ally, deadlines are associated with transactions, and the system attempts to execute a given set of transactions so as to both meet the deadlines and ensure the database consistency. This paper presents an alternative model of real-time database processing in which deadlines are associated with consistency constraints rather than directly with transactions.

Watermarks are the most important tool for dating old, not explicitly dated paper documents. Hence, catalogues and databases of watermarks play an eminent role for the work of medievalist and paper historians. This article presents an integrated software system developed for storage, retrieval, manipulation, digital processing, and identification of watermarks in old manuscripts. The whole processing pipeline beginning with the scanning of watermarks up to their identification is described. Most of these watermarks were captured from manuscripts kept in the Klosterneuburg monastery (Austria).

Routing systems for motorized vehicles in the internet are well known and widely used. But until recently, there had been no possibility to completely design and individually plan a tourist bicycle tour. This paper describes the conceptual design and implementation of such a bicycle routing system which has been operational since July 2001. Design and implementation of the routing system was done by the Research Center for Geoinformatics and Remote Sensing (FZG) at the University of Vechta in coorporation with the organization 'Verbund Oldenburger Münsterland e.V.'. To achieve the desired goals, a server/client architecture was used which was based on commercial GIS, database system, and internet components. It is planned that in the near future the bicycle routing system 'Fahrradies' will be extended with the data of neighboring tourist regions as well as with new functions. It will also prove necessary to adapt the system to the new developments of the underlying GIS software and emerging internet standards. Other options include the possibility to integrate the routing system with online navigation and positioning data in the field using wireless communication technology.

The use of software agents as Database Management System components lead to database systems that may be conflgured and extended to support new requirements. We focus here with the self-tuning feature, which demands a somewhat intelligent behavior that agents could add to traditional DBMS modules. We propose in this paper an agent-based database architecture to deal with automatic index creation.

In order to provide a portable and accurate typing system for the unambiguous characterization of pathogenic Escherichia coli isolates to the scientific community, we have constructed an online database for MultiLocus Sequence Typing of pathogenic E. coli (EcMLST) using current internet and open source technology. The system consists of an XML specification of the E. coli MLST system, and a set of perl modules defining the database tables and generating dynamic web pages for querying the database. It is implemented on a Sun server running the Apache web server. The underlying tier is the MySQL database system. Currently, the database contains nucleotide sequence data and annotated allelic profile data of 15 housekeeping genes for 600 representative E. coli isolates. Access to the central-held typing and epidemiology data is supported by parametric searching, full-text searching, as well as query interface links to the reference center of Shiga Toxin-producing E. coli (STEC, http://www.shigatox.net/stec). EcMLST has been used by public health laboratories and researchers for epidemiology and evolutionary studies. The system can be accessed at

The nested transaction model was introduced to satisfy the requirements of advanced database applications. Moreover, it is currently the basic transaction model for new databases like workflow systems, mobile databases, and objectrelational databases. Though there are several performance evaluation studies of different concurrency control mechanisms in nested transactions, effects of transaction parameters on the overall system performance have not received any attention. In this paper, we study the effects of transactions characteristics on system performance. We developed a detailed simulation model and conducted several experiments to measure the impact of transactions characteristics on the performance. First, the effect of the number of leaves on the performance of nested transactions is investigated under different shaping parameters. Also, effects of the depth of the transaction tree on the system performance are investigated.

Historically, bitmap indexing has provided an important database capability to accelerate queries. However, only a few database systems have implemented these indexes because of the difficulties of modifying fundamental assumptions in the lowlevel design of a database system and in the expectations of customers, both of which have developed in an environment that does not support bitmap indexes. Another problem that arises, and one that may more easily be addressed by a research article, is that there is no definitive design for bitmap indexes; bitmap index designs in Oracle, Sybase IQ, Vertica and MODEL 204 are idiosyncratic, and some of them were designed for older machine architectures. To investigate an efficient design on modern processors, this paper provides details of the Set Query benchmark and a comparison of two research implementations of bitmap indexes. One, called RIDBit, uses the N-ary storage model to organize table rows, and implements a strategy that gracefully switches between the well-known B-tree RID-list structure and a bitmap structure. The other, called FastBit is based on vertical organization of the table data, where all columns are individually stored. It implements a compressed bitmap index, with a linear organization of the bitmaps to optimize disk accesses. Through this comparison, we evaluate the pros and cons of various design choices. Our analysis adds a number of subtleties to the conventional indexing wisdom commonly quoted in the database community.

While many theoretical arguments against or in favor of open source and closed source software development have been presented, the empirical basis for the assessment of arguments and the development of models is still weak. Addressing this research gap, this paper presents the first comprehensive empirical investigation of published vulnerabilities and patches of 17 widely deployed open source and closed source software packages, including operating systems, database systems, web browsers, email clients, and office systems. The empirical analysis uses comprehensive vulnerability data contained in the NIST National Vulnerability Database and a newly compiled data set of vulnerability patches. The results suggest that it is not the particular software development style that determines the severity of vulnerabilities and vendors' patching behavior, but rather the specific application type and the policy of the particular development community, respectively.

Existing commercial database management systems offer little or no functionality to handle the complexity of geoscience data-and other environmental science data-particularly in respect of missing and partially missing (incomplete or imprecise) data items. The emphasis of both the relational theorists (Codd, Date, and others) and the developers of database systems is on commercial applications where only rudimentary treatment of missing data is required, in the form of NULLs, and even these are not handled properly by the SQL language.

This paper discusses the design and implementation of SEQ, a database system with support for sequence data. SEQ models a sequence as an ordered collection of records, and supports a declarative sequence query language based on an algebra of query operators, thereby permitting algebraic query optimization and evaluation. SEQ has been built as a component of the PREDATOR database system that provides support for relational and other kinds of complex data as well.

TESTING RELATIONAL DATABASE USING SQLLint Hassan Reza and Kris Zarns University of North Dakota School of Aerospace Sciences Grand Forks, ND 58202, USA reza@aero.und. edu Abstract – Database systems are an important element of any web based systems. ...

Abstract: Time is one of the most difficult aspects to handle in real world applications such as database systems. Relational database management systems proposed by Codd offer very little built-in query language support for temporal data management. The model itself ...

Manipulating a database system on a quantum computer is an essential aim to benefit from the promising speed-up of quantum computers over classical computers in areas that take a vast amount of storage and processing time such as in databases. In this paper, the ...

he proliferation of file systems, navigational database systems (hierarchical and network). and relational database systems during the past three decades has created difficult problems arising from the need to access heterogeneous files and databases through a single data definition and query language designed under a single data model. This has been the primary motivation for research into multidatabase systems'.' during the past 15 years. An MDBS is a federation of independently developed component database systems (CDBSs). The MDBS provides a homogenizing layer on top of the CDBSs, thus giving users the illusion of a homogeneous system. Because CDBSs operate independently (that is, without central control or distributed coordination), the component databases (CDBs) may include structural and representational discrepancies. or conflicts. called schematic and data heterogeneity. These conflicts mu\t hc r L w l v c c l (homogcnized) s o MDRS users c;in access the underlying C ' D I h with a sinylc uniform clatabasc language rather than ; 1 dillcrcnt database laiiguagc Schema and data conflicts between component databases are a crucial problem in building multidatabase systems. This article presents a comprehensive framework for classifying these conflicts.

In this paper, evolutionary algorithms are explored with the objective of demonstrating that they offer the most efficient and adequate solution to the Index Selection Problem (ISP). The final target is to develop a self-tuning database system requiring little (or no) intervention from experts in physical design. Following the evaluation of the proposal and the discussion of experimental results, conclusions are made regarding the possibilities presented by evolutionary algorithms for future projects.

Database workloads consist of mixes of queries that run concurrently and interact with each other. In this paper, we demonstrate that query interactions can have a significant impact on database system performance. Hence, we argue that it is important to take these interactions into account when characterizing workloads, designing test cases, or developing performance tuning algorithms for database systems. To capture and model query interactions, we propose using an experimental approach that is based on sampling the space of possible interactions and fitting statistical models to the sampled data. We discuss using such an approach for database testing and tuning, and we present some opportunities and research challenges.

We introduce quantum databases, a new database abstraction that allows to defer the making of choices in transactions until an application or user forces the choices by observation. Conceptually, a transaction is in a quantum state -in one of many possible worlds, which one is unknown -until fixed by observation. Practically, our abstraction enables late binding of values read from the database. This allows more transactions to succeed in environments with high contention. This is particularly important for applications in which transactions compete for scarce physical resources represented by data items in the database, such as seats in airline reservation systems or meeting slots in calendaring systems. In such environments, deferral of the assignment of resources to consumers until all constraints are available to the system will lead to more successful transactions. Through entanglement of queries and transactions, a notion that we have explored in previous work, quantum databases can enable collaborative applications with a constraint satisfaction aspect directly within the database system.

Real-world data -especially when generated by distributed measurement infrastructures such as sensor networks -tends to be incomplete, imprecise, and erroneous, making it impossible to present it to users or feed it directly into applications. The traditional approach to dealing with this problem is to first process the data using statistical or probabilistic models that can provide more robust interpretations of the data. Current database systems, however, do not provide adequate support for applying models to such data, especially when those models need to be frequently updated as new data arrives in the system. Hence, most scientists and engineers who depend on models for managing their data do not use database systems for archival or querying at all; at best, databases serve as a persistent raw data store.

Benchmarking graph-oriented database workloads and graph-oriented database systems are increasingly becoming relevant in analytical Big Data tasks, such as social network analysis. In graph data, structure is not mainly found inside the nodes, but especially in the way nodes happen to be connected, i.e. structural correlations. Because such structural correlations determine join fan-outs experienced by graph analysis algorithms and graph

Modern database applications including computer-aided design, multimedia information systems, medical imaging, molecular biology, or geographical information systems impose new requirements on the effective and efficient management of spatial data. Particular problems arise from the need of high resolutions for large spatial objects and from the design goal to use general purpose database management systems in order to guarantee industrial-strength. In the past two decades, various stand-alone spatial index structures have been proposed but their integration into fully-fledged database systems is problematic. Most of these approaches are based on the decomposition of spatial objects leading to replicating index structures. In contrast to common black-and-white decompositions which suffer from the lack of intermediate solutions, we introduce gray intervals which are stored in a spatial index. Additionally, we store the exact information of these gray intervals in a compressed way. These gray intervals are created by using a cost-based decompositioning algorithm which takes the access probability and the decompression cost of them into account. Furthermore, we exploit statistical information of the database objects to find a cost-optimal decomposition of the query objects. The experimental evaluation on the SEQUOIA benchmark test points out that our new concept outperforms the Relational Interval Tree by more than one order of magnitude with respect to overall query response time.

Queries containing outer joins are common in data warehousing applications. Materialized outer-join views could greatly speed up many such queries but most database systems do not allow outer joins in materialized views. In part, this is because outer-join views could not previously be maintained efficiently when base tables are updated. In this paper we show how to efficiently maintain general outer-join views, that is, views composed of selection, projection, inner and outer joins. Foreign-key constraints are exploited to reduce maintenance overhead. Experimental results show that maintaining an outer-join view need not be more expensive than maintaining an inner-join view.

Security facilities of information systems with high security requirements should be consistently and continuously developed, used, and maintained based on some common standards of information security. However, there is no engineering environment that can support all tasks in security engineering consistently and continuously. To construct a security engineering environment, a database that can manage all data concerning all tasks in

Stockholm Syndrome is a paradoxical psychological experience which both intrigues and often frustrates law enforcement and mental health professionals alike. Much attention has been directed toward understanding and defining the contextual variables associated with the development of Stockholm Syndrome. Since it appears that the formation of Stockholm Syndrome may increase the likelihood of hostage survival, discerning the factors that may encourage its occurrence is a priority for crisis negotiators. The purpose of this paper is to (1) analyze crisis situations using actual case examples in which evidence of Stockholm Syndrome has been reported and (2) examine the variables associated with the development of this phenomenon. Case information was obtained from the Hostage Barricade Database System (HOBAS) of the FBI’s Crisis Negotiation Unit. Results of this analysis conclude that some, but not all, factors previously hypothesized as requisite to the development of Stockholm Syndrome find additional support from this case analysis.

Web applications built using Java technologies usually access relational databases via JDBC API. This requires a database system specific JDBC driver to be installed on the application side. On the other hand, a paradigm shift is taking place in web application architectures. Future web applications will be built around Service-Oriented Architectures (SOA) where applications will be assembled using remote "web

This book Databases and Transaction Processing constitutes a standard database textbook for advanced undergraduate and graduate coursesalbeit with a somewhat different focus compared to the established books. As the subtitle An Application-Oriented Approach indicates, the authors put an emphasis on teaching the systematic usage of database systems-rather than concentrating on an in-depth coverage of implementation techniques for building database systems. The rationale for this focus is that many more students will be implementing applications than will actually be implementing database systems. Therefore, the authors set out to present the conceptual and engineering principles underlying the design and implementation of database and transaction processing applications. In order to provide a solid foundation for these principles, the book thoroughly presents the concepts and the theory underlying relational databases, conceptual/relational data modelling, and relational query languages.

AbstractÐIn the past decade, the exponential growth in commodity CPU's speed has far outpaced advances in memory latency. A second trend is that CPU performance advances are not only brought by increased clock rate, but also by increasing parallelism inside the CPU. Current database systems have not yet adapted to these trends and show poor utilization of both CPU and memory resources on current hardware. In this paper, we show how these resources can be optimized for large joins and translate these insights into guidelines for future database architectures, encompassing data structures, algorithms, cost modeling, and implementation. In particular, we discuss how vertically fragmented data structures optimize cache performance on sequential data access. On the algorithmic side, we refine the partitioned hash-join with a new partitioning algorithm called radix-cluster, which is specifically designed to optimize memory access. The performance of this algorithm is quantified using a detailed analytical model that incorporates memory access costs in terms of a limited number of parameters, such as cache sizes and miss penalties. We also present a calibration tool that extracts such parameters automatically from any computer hardware. The accuracy of our models is proven by exhaustive experiments conducted with the Monet database system on three different hardware platforms. Finally, we investigate the effect of implementation techniques that optimize CPU resource usage. Our experiments show that large joins can be accelerated almost an order of magnitude on modern RISC hardware when both memory and CPU resources are optimized.

Database driven Information Systems (IS) have two distinct integrity concerns: static, or data integrity and dynamic integrity. Static integrity addresses situations within a particular database state, or instance and dynamic integrity is concerned with state sequences instead.

In order to handle spatial data efficiently, as required in computer aided design and geo-data applications, a database system needs an mdex mechanism that ti help it retrieve data items quickly accordmg to their spatial locations However, traditional mdexmg methods are not well suited to data oblects of non-zero size located m multidimensional spaces In this paper we describe a dynarmc mdex structure called an R-tree winch meets this need, and give algorithms for searching and updatmg it. We present the results of a series of tests which indicate that the structure performs well, and conclude that it is useful for current database systems m spatial applications

Client-server database systems based on a data shipping model can exploit client memory resources by caching copies of data items across transaction boundaries. Caching reduces the need to obtain data from servers or other sites on the network. In order to ensure that such caching does not result in the violation of transaction semantics, a transactional cache consistency maintenance algorithm is required. Many such algorithms have been proposed in the literature and, as all provide the same functionality, performance is a primary concern in choosing among them. In this article we present a taxonomy that describes the design space for transactional cache consistency maintenance algorithms and show how proposed algorithms relate to one another. We then investigate the performance of six of these algorithms, and use these results to examine the tradeoffs inherent in the design choices identified in the taxonomy. The results show that the interactions among dimensions of the design space can impact performance in many ways, and that classifications of algorithms as simply "pessimistic" or "optimistic" do not accurately characterize the similarities and differences among the many possible cache consistency algorithms.

Efficient methods of processing unanticipated queries are a crucial prerequisite for the success of generalized database management systems. A wide variety of approaches to improve the performance of query evaluation algorithms have been proposed: logic-based and ...

In contrast to space-partitioning index structures, data-partitioning index structures naturally adapt to the actual data distribution which results in a very good query response behavior. Besides efficient query processing, modern database applications including computer-aided design, medical imaging, or molecular biology require fully-fledged database management systems in order to guarantee industrial-strength. In this paper, we show how we can achieve efficient query processing on data-partitioning index structures within general purpose database systems. We reduce the navigational index traversal cost by using "extended index range scans". If a directory node is "largely" covered by the actual query, the recursive tree traversal for this node can beneficially be replaced by a scan on the leaf level of the index instead of navigating through the directory any longer. On the other hand, for highly selective queries, the index is used as usual. In this paper, we demonstrate the benefits of this idea for spatial collision queries on the Relational R-tree. Our experiments with an Oracle9i database system show that our new approach outperforms common index structures and the sequential scan considerably.

The most important feature of a multidatabase system (MDBS) is to provide the global schema with integrating various models of local database systems (LDBS). However, it is difficult to integrate local schemas into the global schema due to the difference of the syntactical and semantic expressions of LDBSs. In this paper, we propose the standard SQL extension for MDBS called by Multidatabase Query Language (MQL). In addition, we analyze semantic conflicts using case studies and provide solutions to the semantic conflicts using MQL.

We describe a new database management system architecture designed for long term evolutionary growth of modular DBMSs. This architecture includes the development of Ada package speci cations for the individual modules. Alternative code bodies can be written corresponding to these package speci cations for variations in desired functionality. These alternative code bodies can also exist side by side, such as a hash structure package along with a B-tree package, or a relational storage module along with an object storage module. Functional speci cations are written in Anna, a formal annotation language for Ada. This e ort does not represent a new data model but rather a new approach to database implementation. This approach can be used to build database systems of any model, including a hybrid relational and object store approach suitable for applications such as Computer Aided Software Engineering (CASE). Our architecture speci cally takes into consideration multi-level security, dis...

Today’s real-time systems (RTS) are characterized by managing large volumes of dispersed data making real-time distributed data processing a reality. Large business houses need to do distributed processing for many reasons, and they often must do it in order to stay competitive. So, efficient database management algorithms and protocols for accessing and manipulating data are required to satisfy timing constraints of supported applications. Therefore, new research in distributed real-time database systems (DRTDBS) is needed to investigate possible ways of applying database systems technology to real-time systems. This paper first discusses the performance issues that are important to DRTDBS, and then surveys the research that has been done so far on the issues like priority assignment policy, commit protocols and optimizing the use of memory in non-replicated/replicated environment pertaining to distributed real time transaction processing. In fact, this study provides a foundation for addressing performance issues important for the management of very large real time data and pointer to other publications in journals and conference proceedings for further investigation of unanswered research questions.

A federated database system (FDBS) is a collection of cooperating database systems that are autonomous and possibly heterogeneous. In this paper, we define a reference architecture for distributed database management systems from system and schema viewpoints and show how various FDBS architectures can be developed. We then define a methodology for developing one of the popular architectures of an FDBS. Finally, we discuss critical issues related to developing and operating an FDBS.