Encyclopedia of Database Systems

2009 Edition

Query Processing and Optimization in Object Relational Databases

  • Johann-Christoph Freytag
Reference work entry
DOI: https://doi.org/10.1007/978-0-387-39940-9_297



In an (object) relational database management system (DBMS) query processing comprises all steps of processing a user submitted query including its execution to compute the requested result. Usually, a user query – for example a SQL query – declaratively describes what should be computed. Then, it is the responsibility of the DBMS to determine how to compute the result by generating a (procedural) query execution plan (QEP) that is semantically equivalent to the original query. Query processing also includes the execution of this generated QEP.

While generating a QEP for a user submitted query the DBMS explores a large number of potential execution alternatives. To choose the best ones among those alternatives requires one or more (query) optimization phases.

Historical Background

In the late 1960s and early 1970s it became clear that existing DBMSs were too complex and cumbersome to use. The programmer was forced to...

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Recommended Reading

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Johann-Christoph Freytag

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