20214518
Extensible Indexing Support in DB2 Universal Database
Publisher Summary Emerging database (DB) applications require the scalable management of a large quantity of complex data, together with traditional business data and flexible querying capabilities for business intelligence. Object-relational databases or universal servers are component database management systems (DBMSs) developed to support applications. They leverage the mature relational database technology that provides scalability, reliability, and recovery. They enable users to introduce application-specific types and methods into a database. These extensibility features can be seen as infrastructure for providing plug-in components that extend the built-in repertoire of database types and functions with support for additional, nonstandard data types. Tables in a database may contain user-defined objects such as geographical shapes, images, and semi-structured or unstructured text documents. This chapter presents a high-level framework of indexing for user-defined types. The framework allows users to concentrate on the semantics of applications and user-defined predicates without being concerned with the low-level details of locking, recovery, buffer management, or balanced search-tree updates. It is tightly integrated with the database engine and enhances the value of underlying access methods, built-in or user-defined, in a database system by supporting indexing on new data types and indexed scans using new predicates.
58268816
Query Optimization in the IBM DB2 Family.
6838561
High Level Indexing of User-Defined Types
35134245
Single Table Access Using Multiple Indexes: Optimization, Execution, and Concurrency Control Techniques
Many data base management systems' query optimizers choose at most one index for accessing the records of a table in a given query, even though many indexes may exist on the table. In spite of the fact that there are some systems which use multiple indexes, very little has been published about the concurrency control or query optimization implications (e.g., deciding how many indexes to use) of using multiple indexes. This paper addresses these issues and presents solutions to the associated problems. Techniques are presented for the efficient handling of record ID lists, elimination of some locking, and determination of how many and which indexes to use. The techniques are adaptive in the sense that the execution strategies may be modified at run-time (e.g., not use some indexes which were to have been used), if the assumptions made at optimization-time (e.g., about selectivities) turn out to be wrong. Opportunities for exploiting parallelism are also identified. A subset of our ideas have been implemented in IBM's DB2 V2R2 relational data base management system.
62021419
IA-32 execution layer: a two-phase dynamic translator designed to support IA-32 applications on Itanium/spl reg/-based systems
IA-32 execution layer (IA-32 EL) is a new technology that executes IA-32 applications on Intel Itanium processor family systems. Currently, support for IA-32 applications on Itanium-based platforms is achieved using hardware circuitry on the Itanium processors. This capability will be enhanced with IA-32 EL - software that will ship with Itanium-based operating systems and will convert IA-32 instructions into Itanium instructions via dynamic translation. In this paper, we describe aspects of the IA-32 execution layer technology, including the general two-phase translation architecture and the usage of a single translator for multiple operating systems. The paper provides details of some of the technical challenges such as precise exception, emulation of FP, MMX, and Intel streaming SIMD extension instructions, and misalignment handling. Finally, the paper presents some performance results.
8746552
A queueing analysis for the denial of service (DoS) attacks in computer networks
In most network security analysis, researchers mainly focus on qualitative studies on security schemes and possible attacks, and there are few papers on quantitative analysis in the current literature. In this paper, we propose one queueing model for the evaluation of the denial of service (DoS) attacks in computer networks. The network under DoS attacks is characterized by a two-dimensional embedded Markov chain model. With this model, we can develop a memory-efficient algorithm for finding the stationary probability distribution which can be used to find other interesting performance metrics such as the connection loss probability and buffer occupancy percentages of half-open connections for regular traffic and attack traffic. Different from previous works in the literature, this paper gives a more general analytical approach to the study of security measures of a computer network under DoS attacks. We hope that our approach opens a new avenue to the quantitative evaluation of more complicated security schemes in computer networks.
5597681
An Ensemble Approach to Learning to Rank
In recent years, 'learning to rank' is a focused approach for information retrieval, which can learn the ranking order given by experts and construct a uniform model to rank for new query. But in practice user queries vary in large diversity, it makes a single learned ranker not representative. Therefore, we propose an ensemble approach to 'learning to rank,' in which a lower generalization error can be gotten by generating a set of rankers and leveraging these rankers for the final prediction. Moreover, two strategies of creating multiple base rankers are proposed to make the ensemble more effective for information retrieval. The experiment results on two real world datasets indicate that the proposed approach can outperform the original 'learning to rank' methods significantly.
18702956
A Dynamic Hidden Markov Random Field Model for Foreground and Shadow Segmentation
This paper proposes a dynamic hidden Markov random field (DHMRF) model for foreground object and moving shadow segmentation in indoor video scenes. Given an image sequence, temporal dependencies of consecutive segmentation fields and spatial dependencies within each segmentation field are unified in the novel dynamic probabilistic model that combines the hidden Markov model (HMM) and the Markov random field (MRF). An efficient approximate filtering algorithm is derived for the DHMRF model to recursively estimate the segmentation field from the history of observed images. The foreground and shadow segmentation method integrates both intensity and edge information: Moreover, models of background, shadow, and edge information are updated adoptively for nonstationary background processes. Experimental results show that the proposed approach can accurately detect moving objects and their cast shadows even in monocular grayscale video sequences
5690166
Developing a database for proteomic analysis of extracytosolic plant proteins
Extracytosolic plant proteins are involved in numerous processes including nutrient acquisition, communication with other soil organisms, protection from pathogens, and resistant to disease and toxic metals. We have developed an online database to provide the plant biology community with relevant information about extracytosolic plant proteins. Data for Brassica napus (canola) proteins identified using proteomics tools can be accessed using this database. Several textual and graphical query capabilities allow biologists to populate and query this database. Results are displayed with active links to other databases. The system has an open API allowing other applications to access this database as a Web service. In addition, the database is augmented with a repository of tools that can be used in data analysis and mining tasks.