Optimization of nested queries in a complex object model

H.J. Steenhagen; Hennie J. Steenhagen; Peter M.G. Apers; Henk Blanken

doi:10.1007/3-540-57818-8_62

Optimization of nested queries in a complex object model

H.J. Steenhagen, Hennie J. Steenhagen, Peter M.G. Apers, Henk Blanken

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Academic › peer-review

13 Citations (Scopus)

79 Downloads (Pure)

Abstract

Transformation of nested SQL queries into join queries is advantageous because a nested SQL query can be looked upon as a nested-loop join, which is just one of the several join implementations that may be available in a relational DBMS. In join queries, dangling (unmatched) operand tuples are lost, which causes a problem in transforming nested queries having the aggregate function COUNT between query blocks-a problem that has become well-known as the COUNT bug. In the relational context, the outerjoin has been employed to solve the COUNT bug. In complex object models supporting an SQL-like query language, transformation of nested queries into join queries is an important optimization issue as well. The COUNT bug turns out to be a special case of a general problem being revealed in a complex object model. To solve the more general problem, we introduce the nest join operator, which is a generalization of the outerjoin for complex objects.

Original language	English
Title of host publication	Advances in database technology - EDBT '94
Editors	Matthias Jarke, Janis Bubenko, Keith Jeffery
Place of Publication	Berlin
Publisher	Springer
Pages	337-350
ISBN (Print)	3-540-57818-8
DOIs	https://doi.org/10.1007/3-540-57818-8_62
Publication status	Published - 28 Mar 1994
Event	4th International Conference on Extending Database Technology, EDBT 1994 - Cambridge, United Kingdom Duration: 28 Mar 1994 → 31 Mar 1994 Conference number: 4

Publication series

Name	Lecture notes in computer science
Publisher	Springer
Volume	779
ISSN (Print)	0302-9743
ISSN (Electronic)	1611-3349

Conference

Conference	4th International Conference on Extending Database Technology, EDBT 1994
Abbreviated title	EDBT
Country	United Kingdom
City	Cambridge
Period	28/03/94 → 31/03/94

Keywords

METIS-118956
IR-96073

Access to Document

10.1007/3-540-57818-8_62

chp_10.1007_3-540-57818-8_62
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Steenhagen, H. J., Steenhagen, H. J., Apers, P. M. G., & Blanken, H. (1994). Optimization of nested queries in a complex object model. In M. Jarke, J. Bubenko, & K. Jeffery (Eds.), Advances in database technology - EDBT '94 (pp. 337-350). (Lecture notes in computer science; Vol. 779). Berlin: Springer. https://doi.org/10.1007/3-540-57818-8_62

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title = "Optimization of nested queries in a complex object model",

abstract = "Transformation of nested SQL queries into join queries is advantageous because a nested SQL query can be looked upon as a nested-loop join, which is just one of the several join implementations that may be available in a relational DBMS. In join queries, dangling (unmatched) operand tuples are lost, which causes a problem in transforming nested queries having the aggregate function COUNT between query blocks-a problem that has become well-known as the COUNT bug. In the relational context, the outerjoin has been employed to solve the COUNT bug. In complex object models supporting an SQL-like query language, transformation of nested queries into join queries is an important optimization issue as well. The COUNT bug turns out to be a special case of a general problem being revealed in a complex object model. To solve the more general problem, we introduce the nest join operator, which is a generalization of the outerjoin for complex objects.",

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Steenhagen, HJ, Steenhagen, HJ, Apers, PMG & Blanken, H 1994, Optimization of nested queries in a complex object model. in M Jarke, J Bubenko & K Jeffery (eds), Advances in database technology - EDBT '94. Lecture notes in computer science, vol. 779, Springer, Berlin, pp. 337-350, 4th International Conference on Extending Database Technology, EDBT 1994, Cambridge, United Kingdom, 28/03/94. https://doi.org/10.1007/3-540-57818-8_62

Optimization of nested queries in a complex object model. / Steenhagen, H.J.; Steenhagen, Hennie J.; Apers, Peter M.G.; Blanken, Henk.

Advances in database technology - EDBT '94. ed. / Matthias Jarke; Janis Bubenko; Keith Jeffery. Berlin : Springer, 1994. p. 337-350 (Lecture notes in computer science; Vol. 779).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Academic › peer-review

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