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Parallel sort-merge object-oriented collection join algorithms

COMPUTER SYSTEMS SCIENCE AND ENGINEERING 2002年第3期17卷 145-158页

作者： Taniar, D Rahayu, JW Monash Univ Sch Business Syst Clayton Vic 3800 Australia La Trobe Univ Dept Comp Sci & Comp Engn Bundoora Vic 3083 Australia

One of the differences between relational and object-oriented databases (OODB) is that attributes in OODB can be of a collection type (e.g. sets, lists, arrays, and bags) as well as a simple type (e.g. integer, string). Consequently, explicit join queries in OODB may be based on collection attributes. We call this type of join Collection join queries. There are three different kinds of collection join queries, namely: Collection-Equi join, Collection-Intersect join, and Sub-Collection join. Basically, a collection-equi join query checks an equality of both collection operands, whereas a collection-intersect join query checks whether there is an intersection between the two join collection attributes. Sub-collection join queries check whether one collection is a sub-collection of the other. In this paper, we present parallel join algorithms for the above three collection join query types based on the sort-merge technique. Sonic of the proposed algorithms employ a nested-loop construct as well. We also outline the complexity of collection merging in the algorithm. Parallel join algorithms are normally composed of two stages, data partitioning and local join. For the data partitioning stage in collection-intersect and sub-collection join algorithms, we propose a 'Divide and Partial Broadcast' partitioning. The proposed join algorithms play an important role in parallel object-oriented query processing, due to their superiority over the conventional join methods, which are usually in a form of relational division, and also the inefficiency of original join predicates processing.

关键词： parallel query processing parallel join object-oriented join queries collection types object-oriented Databases and sort-merge join

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PARALLEL SORT-HASH object-oriented COLLECTION join ALGORITHMS FOR SHARED-MEMORY MACHINES

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Parallel Algorithms and Applications 2002年第2期17卷 85-126页

作者： David Taniar - E-mail: David.Taniar@infotech.monash.edu.au[a] J. Wenny Rahayu[b] [a] School of Business Systems Monash University Clayton Vic Australia [b] Department of Computer Science and Computer Engineering La Trobe University Bundarra Vic Australia

Collection join queries are join queries based on collection attributes (i.e. non-atomic attributes), which are common in object-oriented databases. We have identified three different kinds of collection join queries, namely;cullection-equijoin,collection-intersectjoin, andsub-collectionjoin. In this paper, we propose parallel join algorithms for these three collection join query types based on a combination of sort and hash methods, which we callparallel sort-hash, collection join algorithms. The proposed join algorithms play an important role in parallel object-oriented query processing, due to their superiority over the conventional join methods which are usually in a form of relational division, and also the inefficiency of the original join predicate processing. In our implementation of these algorithms on a shared-memory machine, we show that the combination between sort and hash methods is proven to be better than the conventional sort-merge and nested-loop based parallel join processing

关键词： Parallel query processing Parallel join object-oriented join queries Collection types object-oriented databases Parallel databases

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