A configurable type hierarchy index for OODB |
| |
Authors: | Thomas A Mueck Martin L Polaschek |
| |
Affiliation: | Abteilung für Data Engineering, Universit?t Wien, Rathausstr. 19/4, A-1010 Wien, Austria; e-mail: {mueck, polaschek\protect}@ifs.univie.ac.at, AT
|
| |
Abstract: | With respect to the specific requirements of advanced OODB applications, index data structures for type hierarchies in OODBMS
have to provide efficient support for multiattribute queries and have to allow index optimization for a particular query profile.
We describe the multikey type index and an efficient implementation of this indexing scheme. It meets both requirements: in addition to its multiattribute query
capabilities it is designed as a mediator between two standard design alternatives, key-grouping and type-grouping. A prerequisite
for the multikey type index is a linearization algorithm which maps type hierarchies to linearly ordered attribute domains
in such a way that each subhierarchy is represented by an interval of this domain. The algorithm extends previous results
with respect to multiple inheritance. The subsequent evaluation of our proposal focuses on storage space overhead as well
as on the number of disk I/O operations needed for query execution. The analytical results for the multikey type index are
compared to previously published figures for well-known single-key search structures. The comparison clearly shows the superiority
of the multikey type index for a large class of query profiles.
Edited by E. Bertino. Received October 7, 1996 / Accepted March 28, 1997 |
| |
Keywords: | : OODB – Access methods – Indexing – Type hierarchies – Multiple inheritance |
本文献已被 SpringerLink 等数据库收录! |
|