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IEICE TRANSACTIONS on Information

Optimization of Join-Type Queries in Nested Relational Databases

Yaxin LI, Hiroyuki KITAGAWA, Nobuo OHBO

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Summary :

Nested relational models were proposed as natural extensions of the relational model to support new emerging database applications. Prototype implementations of nested relational database systems (NRDBSs) have been done by some research groups. However, there remain many research issues on nested relations. One important issue is query processing, in particular query optimization. In NRDBSs, efficient execution of queries involving hierarchical data structures inherent in nested relations is required. In this paper, we focus on two join-type operations on nested relations: nested join and embed, and propose an algorithm to derive a cost optimal execution sequence of nested joins and embeds for a given query graph. The cost optimality of the derived sequence is formally proved. The complexity of the algorithm is proved to be O(N 2), when N nested relations are included in the query graph.

Publication
IEICE TRANSACTIONS on Information Vol.E77-D No.6 pp.648-659
Publication Date
1994/06/25
Publicized
Online ISSN
DOI
Type of Manuscript
PAPER
Category
Databases

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