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Comments on "Hash-Based and Index-Based Join Algorithms for Cube and Ring Connected Multicomputers"
September 1991 (vol. 3 no. 3)
pp. 387-389

The cost distributions of both the parallel hybrid-hash join and the parallel join-index join algorithms proposed in the above-named work are presented in more detail. The result shows that almost the entire relation may need to be retrieved from disk, though the join selectivity is low. A table of semi-join selectives and cube sizes is given to show the condition that the join-index method performs better than the hybrid-hash method, i.e., the really low selectivity for the join-index method. An error in one of the cost formulas is corrected, and a more efficient method on the final join in the join-index method is proposed.

[1] P. Valduriez, "Join indices,"ACM Trans. Database Syst., vol. 12, pp. 218-246, June 1987.
[2] S. B. Yao, "Approximating block accesses in database organizations,"Commun. ACM, vol. 20, pp. 260-261, Apr. 1977.

Index Terms:
cube connected multicomputers; index-based join algorithms; ring connected multicomputers; parallel hybrid-hash join; parallel join-index join algorithms; semi-join selectives; cube sizes; database theory; distributed databases; indexing
J.-Y. Tien, W.-P. Yang, "Comments on "Hash-Based and Index-Based Join Algorithms for Cube and Ring Connected Multicomputers"," IEEE Transactions on Knowledge and Data Engineering, vol. 3, no. 3, pp. 387-389, Sept. 1991, doi:10.1109/69.91050
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