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Poor Performance Of Native Full Outer Join (Doc ID 731209.1)

Last updated on FEBRUARY 21, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 9.0.1.0 to 10.2.0.4 [Release 9.0.1 to 10.2]
Information in this document applies to any platform.
This problem can occur on any platform.

Symptoms

Performance of some queries using  native full outer join syntax available  since Oracle 9i version is slower for some queries compare with  the equivalent queries rewritten  as  UNION ALL of two separate subqueries,  i.e. without using full outer join syntax.  In some cases performance difference could be two and more  times.  

Changes

 

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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