Eager Aggregation and Lazy Aggregation.

Weipeng P. Yan, Per-Åke Larson: Eager Aggregation and Lazy Aggregation. VLDB 1995: 345-357

@inproceedings{DBLP:conf/vldb/YanL95,
  author    = {Weipeng P. Yan and
               Per-{\AA}ke Larson},
  editor    = {Umeshwar Dayal and
               Peter M. D. Gray and
               Shojiro Nishio},
  title     = {Eager Aggregation and Lazy Aggregation},
  booktitle = {VLDB'95, Proceedings of 21th International Conference on Very
               Large Data Bases, September 11-15, 1995, Zurich, Switzerland},
  publisher = {Morgan Kaufmann},
  year      = {1995},
  isbn      = {1-55860-379-4},
  pages     = {345-357},
  ee        = {db/conf/vldb/YanL95.html},
  crossref  = {DBLP:conf/vldb/95},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}

Abstract

Efficient processing of aggregation queries is essential for decision support applications. This paper describes a class of query transformations, called eager aggregation and lazy aggregation, that allows a query optimizer tomove group-by operations up and down the query tree. Eager aggregation partially pushes a group-by past a join. After a group-by is partially pushed down, we still need to perform the original group-by in the upper query block. Eager aggregation reduces the number of input rows to the join and thus may result in a better overall plan. The reverse transformation, lazy aggregation, pulls a group-by above a join and combines two group-by operations into one. This transformation is typically of interest when an aggregation query references a grouped view (a view containing a group-by). Experimental results show that the technique is very beneficial for queries in the TPC-D benchmark.

Copyright © 1995 by the VLDB Endowment. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by the permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from the Endowment.

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Printed Edition

Umeshwar Dayal, Peter M. D. Gray, Shojiro Nishio (Eds.): VLDB'95, Proceedings of 21th International Conference on Very Large Data Bases, September 11-15, 1995, Zurich, Switzerland. Morgan Kaufmann 1995, ISBN 1-55860-379-4
Contents

References

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[CS95]: ...
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[PHH92]: Hamid Pirahesh, Joseph M. Hellerstein, Waqar Hasan: Extensible/Rule Based Query Rewrite Optimization in Starburst. SIGMOD Conference 1992: 39-48
[Raa95]: ...
[Yan94]: ...
[Yan95]: ...
[YL94]: Weipeng P. Yan, Per-Åke Larson: Performing Group-By before Join. ICDE 1994: 89-100
[YL95]: ...