PL/SQL and the CBO

  • Jože Senegačnik


Several years ago, I made a presentation at the Independent Oracle Users Group conference, IOUG Live 2005, with the title “The Extensible Optimizer.” It’s been quite a long time since that presentation, but many people, especially developers, still are not aware that the cost-based optimizer (CBO) needs some extra input whenever you use a custom PL/SQL function in the WHERE clause of a SQL statement. I have seen so many applications performing poorly because they were using PL/SQL functions in SQL statements without arming the CBO with additional knowledge about those functions. Hence this chapter, in which I will show you how to help the CBO prepare optimal execution plans when using PL/SQL functions as part of your query conditions.


Execution Plan Query Plan Domain Index Equality Predicate Clause Default 


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Copyright information

© Melanie Caffrey, Pete Finnigan, Randolf Geist, Alex Gorbachev, Tim Gorman, Connie Green, Charles Hooper, Jonathan Lewis, Niall Litchfield, Karen Morton, Robyn Sands, Jože Senegačnik, Uri Shaft, Riyaj Shamsudeen, Jeremiah Wilton, Graham Wood 2010

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  • Jože Senegačnik

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