Showing papers by "Hiroyuki Kitagawa published in 1993"

Evaluation of signature files as set access facilities in OODBs

Abstract: Object-oriented database systems (OODBs) need efficient support for manipulation of complex objects In particular, support of queries involving evaluations of set predicates is often required in handling complex objects In this paper, we propose a scheme to apply signature file techniques, which were originally invented for text retrieval, to the support of set value accesses, and quantitatively evaluate their potential capabilities Two signature file organizations, the sequential signature file and the bit-sliced signature file, are considered and their performance is compared with that of the nested index for queries involving the set inclusion operator (⊆) We develop a detailed cost model and present analytical results clarifying their retrieval, storage, and update costs Our analysis shows that the bit-sliced signature file is a very promising set access facility in OODBs

Estimation of False Drops in Set-valued Object Retrieval with Signature Files

Abstract: Advanced database systems have to support complex data structures as treated in object-oriented data models and nested relational data models. In particular, efficient processing of set-valued object retrieval (simply, set retrieval) is indispensable for such systems. In the previous paper [6], we proposed the use of signature files as efficient set retrieval facilities and showed their potential capabilities based on a disk page access cost model. Retrieval with signature files is always accompanied by mismatches called false drops, and it is very important in designing signature files to properly control the false drops.