2593477
A Study of Index Structures for a Main Memory Database Management System
One approach to achieving high performance in a database management system is to store the database in main memorv rather than on disk. -One can then design new data structures aid algorithms oriented towards making eflicient use of CPU cycles and memory space rather than minimizing disk accesses and &ing disk space efliciently. In this paper we present some results on index structures from an ongoing study of main memory database management systems. We propose a new index structure, the T Tree, and we compare it to existing index structures in a main memory database environment. Our results indicate that the T Tree provides good overall performance in main memory.
16894136
Query processing in main memory database management systems
Most previous work in the area of main memory database systems has focused on the problem of developing query processing techniques that work well with a very large buffer pool. In this paper, we address query processing issues for memory resident relational databases, an environment with a very different set of costs and priorities. We present an architecture for a main memory DBMS, discussing the ways in which a memory resident database differs from a disk-based database. We then address the problem of processing relational queries in this architecture, considering alternative algorithms for selection, projection, and join operations and studying their performance. We show that a new index structure, the T Tree, works well for selection and join processing in memory resident databases. We also show that hashing methods work well for processing projections and joins, and that an old join method, sort-merge, still has a place in main memory.
5780278
A Status Report on the oo7 OODBMS Benchmarking Effort
The OO7 Benchmark was first published in 1993, and has since found a home in the marketing literature of various object-oriented database management system (OODBMS) vendors. The OO7 Benchmark (as published) was the initial result of an ongoing OODBMS performance evaluation effort at the University of Wisconsin. This paper provides an update on the status of the effort on two fronts: single-user and multi-user. On the single-user front, we review and critique the design of the initial OO7 Benchmark. We discuss some of its faults, the reasons for those faults, and things that might be done to correct them. On the multi-user front, we describe our current work on the development of a multi-user benchmark for OODBMSs. This effort includes changes and extensions to the OO7 database and the design of a family of interesting multi-user workloads.
1445354
Accurate modeling of the hybrid hash join algorithm
The join of two relations is an important operation in database systems. It occurs frequently in relational queries, and join performance is a significant factor in overall system performance. Cost models for join algorithms are used by query optimizers to choose efficient query execution strategies. This paper presents an efficient analytical model of an important join method, the hybrid hash join algorithm, that captures several key features of the algorithm's performance—including its intra-operator parallelism, interference between disk reads and writes, caching of disk pages, and placement of data on disk(s). Validation of the model against a detailed simulation of a database system shows that the response time estimates produced by the model are quite accurate.
5949420
Indexing Alternatives for Multiversion Locking
In this paper, we present several options for extending single-version indexing schemes for use with multiversion two-phase locking. The proposed options are orthogonal to the underlying indexing structure (e.g., hashing or B+ trees). The options differ in where they place references to individual versions; this version selection information is placed either with the data or in the leaf entries of one or more indices. We also briefly summarize the results of a performance study showing that storing version selection information with the data is usually the best option because it keeps indices smaller, thus enabling a larger fraction of the indices to remain cached in the buffer pool.
6255878
Towards heterogeneous multimedia information systems: the Garlic approach
Provides an overview of the Garlic project, a new project at the IBM Almaden Research Center. The goal of this project is to develop a system and associated tools for the management of large quantities of heterogeneous multimedia information. Garlic permits traditional and multimedia data to he stored in a variety of existing data repositories, including databases, files, text managers, image managers, video servers, and so on; the data is seen through a unified schema expressed in an object-oriented data model and can be queried and manipulated using an object-oriented dialect of SQL, perhaps through an advanced query/browser tool that we are also developing. The Garlic architecture is designed to be extensible to new kinds of data repositories, and access efficiency is addressed via a "middleware" query processor that uses database query optimization techniques to exploit the native associative search capabilities of the underlying data repositories.<<ETX>>