Distributed-query optimization in fragmented data-base systems

Thesis/Dissertation · Sat Aug 01 04:00:00 EDT 1987

DOI:https://doi.org/10.2172/7183881· OSTI ID:7183881

Chen, J S.J.

Join is the most critical operation in distributed-query optimization. In this thesis, the problem of optimizing multiple joins in fragmented data-base systems on both broadcast - and nonbroadcast-type computer networks is analyzed. Semantic information associated with fragments are used to eliminate unnecessary processing. Data redundancy is considered. More than one physical copy of a fragment is allowed to be used in a strategy to achieve more parallelism. In the proposed approach, the problem of optimizing multiple joins is decomposed into two subproblems: the problem of finding a good join sequence and the problem of optimizing each two-way join in the sequence. A dynamic-programming algorithm is developed for determining a join sequence. During intermediate steps of the join sequence, we have the join results remaining fragmented to achieve more parallelism and allow more local executions. All the partial results are assembled at the last two-way join. If the network has broadcast capability, graph models are introduced to represent two-way joins. The two-way join optimization problems are mapped into equivalent graph minimum-weight vertex cover problems. An algorithm based on network flow is developed for optimizing two-way joins with results fragmented.

• Research Organization: University of Southern California, Los Angeles, CA (United States))
• Sponsoring Organization: National Science Foundation (NSF); Department of Defense Joint Services Electronics Program
• OSTI ID: 7183881
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
990210* -- Supercomputers-- (1987-1989)
ALGORITHMS
COMPUTER NETWORKS
DATA PROCESSING
DISTRIBUTED DATA PROCESSING
MATHEMATICAL LOGIC
OPTIMIZATION
PARALLEL PROCESSING
PROCESSING
PROGRAMMING