We propose query optimization techniques that fully utilize the advantages of path indexes in object-oriented database systems. Although path indexes provide an e cient access to complex objects, little research has been done on query optimization that fully utilize path indexes. We rst devise a generalized index intersection technique, adapted to the structure of the path index extended from conventional indexes, for utilizing multiple (path) indexes to access each class in a query. We then propose the query graph reduction algorithm that replaces the classes in the query graph with path index scans; we call the resultant query graph reduced query graph (RQG). We nally present the search algorithm that nds the least-cost evaluation plan from RQG based on a cost model. Proposed query optimization techniques enhance database performance by using path indexes instead of direct accesses to data in the evaluating queries. Keywords object-oriented databases, query optimization, path indexes, cost model.
Multipurpose buildings that have an underground mega mall require distinguished functional considerations compared to small conventional underground spaces. Thus, this study starts with an assumption that architects' knowledge and personal decisions may not be reliable and valid in a massive multipurpose underground mall, because it is beyond general sense in terms of size and function. Especially, when considering safety issues, an architect's personal subjective decisions should be evaluated with scientific and objective criteria. Therefore, the intention of this study is to present an emergency exit and staircase planning method based on a mathematical model of optimized algorithm. The fundamental notions of the mathematical model and optimized algorithm that this study has developed for architectural planning, practically adapted the theoretical and mechanical principal that has been used in the field of industrial engineering for many decades. Consequently, the developed algorithm was able to prove that it could indicate the most efficient exit/staircase location for a certain space and assign it based on quantitative analysis.
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