Optimization and Dataflow Algorithms for Nested Tree Queries.

M. Muralikrishna: Optimization and Dataflow Algorithms for Nested Tree Queries. VLDB 1989: 77-85
  author    = {M. Muralikrishna},
  editor    = {Peter M. G. Apers and
               Gio Wiederhold},
  title     = {Optimization and Dataflow Algorithms for Nested Tree Queries},
  booktitle = {Proceedings of the Fifteenth International Conference on Very
               Large Data Bases, August 22-25, 1989, Amsterdam, The Netherlands},
  publisher = {Morgan Kaufmann},
  year      = {1989},
  isbn      = {1-55860-101-5},
  pages     = {77-85},
  ee        = {db/conf/vldb/Muralikrishna89.html},
  crossref  = {DBLP:conf/vldb/89},
  bibsource = {DBLP,}


The SQL language allows users to express queries that have nested subqueries inthem. Optimization of nested queries has received considerable attention over the last few years. Most of the previous optimization work has assumed that at most one block is nested within any given block. The solutions presented in the literature for the general case (where an arbitrary number of blocks are nested within a block) have either been incorrect or have dealt with a restricted subset of queries. The two main contributions of this paper are: (1) optimization strategies for queries that have an arbitrary number of blocksnested within any given block, and (2) a new dataflow algorithm for the execution of nested queries, involving oneor more outer joins, in a multi-processor environment such as the one found in GAMMA. The new algorithm cuts down on message and CPU costs over conventional dataflow algorithms.

Copyright © 1989 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.

Online Paper

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Printed Edition

Peter M. G. Apers, Gio Wiederhold (Eds.): Proceedings of the Fifteenth International Conference on Very Large Data Bases, August 22-25, 1989, Amsterdam, The Netherlands. Morgan Kaufmann 1989, ISBN 1-55860-101-5


Morton M. Astrahan, Donald D. Chamberlin: Implementation of a Structured English Query Language. Commun. ACM 18(10): 580-588(1975) BibTeX
Umeshwar Dayal: Of Nests and Trees: A Unified Approach to Processing Queries That Contain Nested Subqueries, Aggregates, and Quantifiers. VLDB 1987: 197-208 BibTeX
David J. DeWitt, Robert H. Gerber, Goetz Graefe, Michael L. Heytens, Krishna B. Kumar, M. Muralikrishna: GAMMA - A High Performance Dataflow Database Machine. VLDB 1986: 228-237 BibTeX
Richard A. Ganski, Harry K. T. Wong: Optimization of Nested SQL Queries Revisited. SIGMOD Conference 1987: 23-33 BibTeX
Won Kim: On Optimizing an SQL-like Nested Query. ACM Trans. Database Syst. 7(3): 443-469(1982) BibTeX

Referenced by

  1. César A. Galindo-Legaria, Arnon Rosenthal: Outerjoin Simplification and Reordering for Query Optimization. ACM Trans. Database Syst. 22(1): 43-73(1997)
  2. Pedro Celis, Hansjörg Zeller: Subquery Elimination: A Complete Unnesting Algorithm for an Extended Relational Algebra. ICDE 1997: 321
  3. Mitch Cherniack, Stanley B. Zdonik: Rule Languages and Internal Algebras for Rule-Based Optimizers. SIGMOD Conference 1996: 401-412
  4. Gary C. K. Lam, Vincent Y. Lum, Kam-Fai Wong: On the Issues of Expressiveness and Portability of Chiql. DASFAA 1995: 164-171
  5. César A. Galindo-Legaria: Outerjoins as Disjunctions. SIGMOD Conference 1994: 348-358
  6. Hennie J. Steenhagen, Peter M. G. Apers, Henk M. Blanken: Optimization of Nested Queries in a Complex Object Model. EDBT 1994: 337-350
  7. Sophie Cluet, Guido Moerkotte: Nested Queries in Object Bases. DBPL 1993: 226-242
  8. M. Muralikrishna: Improved Unnesting Algorithms for Join Aggregate SQL Queries. VLDB 1992: 91-102
  9. Daniel F. Lieuwen, David J. DeWitt: A Transformation-Based Approach to Optimizing Loops in Database Programming Languages. SIGMOD Conference 1992: 91-100
  10. César A. Galindo-Legaria, Arnon Rosenthal: How to Extend a Conventional Optimizer to Handle One- and Two-Sided Outerjoin. ICDE 1992: 402-409
  11. Daniel F. Lieuwen, David J. DeWitt: Optimizing Loops in Database Programming Languages. DBPL 1991: 287-305
  12. Arnon Rosenthal, César A. Galindo-Legaria: Query Graphs, Implementing Trees, and Freely-Reorderable Outerjoins. SIGMOD Conference 1990: 291-299
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