Poor Performance Of Native Full Outer Join
Last updated on SEPTEMBER 15, 2016
Applies to:Oracle Server - Enterprise Edition - Version: 18.104.22.168 to 10.2.0.4
This problem can occur on any platform.
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.
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