Academic literature on the topic 'Information storage and retrieval systems Data structures (Computer science)'

Thesis (M.S.)--University of Missouri-Columbia, 2007.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Apr. 9, 2009). Includes bibliographical references.

We live in the Information Age. The effective use of information to manage organizational resources is the key to an organization's competitive power. Thus, a database plays a major role in the Information Age. A well designed database contains relevant, nonredundant, and consistent data. However, a well designed database is rarely achieved in practice. One major reason for this problem is the lack of effective support for logical database design. Since the late 1980s, various methodologies for database design have been introduced, based on the relational model, the functional model, the semantic database model, and the entity structure model. They all have, however, a common drawback: the successful design of database systems requires the experience, skills, and competence of a database analyst/designer. Unfortunately, such database analyst/designers are a scarce resource in organizations. The Structured Entity Model (SEM) method, as an alternative diagrammatic method developed by this research, facilitates the logical design phases of database system development. Because of the hierarchical structure and decomposition constructs of SEM, it can help a novice designer in performing top-down structured analysis and design of databases. SEM also achieves high semantic expressiveness by using a frame representation for entities and three general association categories (aspect, specialization, and multiple decomposition) for relationships. This also enables SEM to have high potential as a knowledge representation scheme for an integrated heterogeneous database system. Unlike most methods, the SEM method does not require designers to have knowledge of normalization theory in order to design a logical database. Thus, an end-user will be able to complete logical database design successfully using this approach. In this research, existing data models used for a logical database design were first studied. Second, the framework of SEM and the design approach using SEM were described and then compared with other data models and their use. Third, the effectiveness of the SEM method was validated in two experiments using novice designers and by a case analysis. In the final chapter of this dissertation, future research directions, such as the design of a logical database design expert system based on the SEM method and applications of this approach to other problems, such as the problems in integration of multiple databases and in an intelligent mail system, are discussed.

In Chapter 2, several other relational database systems will be reviewed. The primary goal of each analysis will be to identify the logical and physical approaches to data representation, as well as the user interface. Chapters 3 and 4 identify the physical and logical structure of the experimental disk-resident spatial information system developed for this project. As will be seen, this experimental system combines features of existing relational databases with new approaches to represent and manipulate information in a database. The Query Language Interpreter will be presented in Chapter 5. Through the interpreter, a database user can issue a variety of commands to perform database operations, as well as create sophisticated program control structures. Chapters 6-8 discuss the security, integrity, and recovery aspects of the disk-resident system. During the development of this project, various implementation problems were encountered. These problems and solutions are presented in Chapter 9. Chapter 10 discusses the performance of the disk-resident system. Statistics are presented comparing how the database commands performed when run under a variety of test environments. Chapter 11 uses the results from earlier chapters to draw conclusions concerning the disk-resident system and presents some directions for future work. Following the bibliography are related appendices that illustrate the various types of files recognized by the query language interpreter.<br>Master of Science

This thesis identifies a problem in the current practice for storage of locational data of entities in the cadastral layer of a land information system (LIS), and presents as a solution an information model that uses an object-oriented paradigm.

Knowledge has always been a decisive factor of humankind's social evolutions. Collecting the world's knowledge is one of the greatest challenges of our civilization. Knowledge involves the use of information but information is not knowledge. It is a way of acquiring and understanding information. Improving the visibility and the accessibility of information requires to organize it efficiently. This thesis focuses on this general purpose.<p><p>A fundamental objective of computer science is to store and retrieve information efficiently. This is known as the dictionary problem. A dictionary asks for a data structure which allows essentially the search operation. In general, information that is important and popular at a given time has to be accessed faster than less relevant information. This can be achieved by dynamically managing the data structure periodically such that relevant information is located closer from the search starting point. The second part of this thesis is devoted to the development and the understanding of self-adjusting dictionaries in various models of computation. In particular, we focus our attention on dictionaries which do not have any knowledge of the future accesses. Those dictionaries have to auto-adapt themselves to be competitive with dictionaries specifically tuned for a given access sequence. <p><p>This approach, which transforms the information structure, is not always feasible. Reasons can be that the structure is based on the semantic of the information such as categorization. In this context, the search procedure is linked to the structure itself and modifying the structure will affect how a search is performed. A solution developed to improve search in static structure is the hotlink assignment. It is a way to enhance a structure without altering its original design. This approach speeds up the search by creating shortcuts in the structure. The first part of this thesis is devoted to this approach.<br>Doctorat en Sciences<br>info:eu-repo/semantics/nonPublished

We are surrounded by an increasing number of devices and applications that produce a huge quantity of machine generated data. Almost all the machine data contains some element of security information that can be used to discover, monitor and investigate security events.The work proposes a pseudo-random access compressed storage method for log data to be used with an information retrieval system that in turn provides the ability to search and correlate log data and the corresponding events. We explain the method for converting log files into distinct events and storing the events in a compressed file. This yields an entry identifier for each log entry that provides a pointer that can be used by indexing methods. The research also evaluates the compression performance penalties encountered by using this storage system, including decreased compression ratio, as well as increased compression and decompression times.

Extreme scale data management in high performance computing requires consideration of the end-to-end scientific workflow process. Of particular importance for runtime performance, the write-read cycle must be addressed as a complete unit. Any optimization made to enhance writing performance must consider the subsequent impact on reading performance. Only by addressing the full write-read cycle can scientific productivity be enhanced. The ADIOS middleware developed as part of this thesis provides an API nearly as simple as the standard POSIX interface, but with the flexibilty to choose what transport mechanism(s) to employ at or during runtime. The accompanying BP file format is designed for high performance parallel output with limited coordination overheads while incorporating features to accelerate subsequent use of the output for reading operations. This pair of optimizations of the output mechanism and the output format are done such that they either do not negatively impact or greatly improve subsequent reading performance when compared to popular self-describing file formats. This end-to-end advantage of the ADIOS architecture is further enhanced through techniques to better enable asychronous data transports affording the incorporation of 'in flight' data processing operations and pseudo-transport mechanisms that can trigger workflows or other operations.