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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Created: (DERBY-4742) Make outer join reordering work for right outer joins
Date Mon, 12 Jul 2010 18:45:50 GMT
Make outer join reordering work for right outer joins

                 Key: DERBY-4742
                 URL: https://issues.apache.org/jira/browse/DERBY-4742
             Project: Derby
          Issue Type: Improvement
          Components: SQL
    Affects Versions:
            Reporter: Dag H. Wanvik

Currently, Derby only attempts to reorder (into left deep) left outer join queries. Right
outer join queries are commented out, apparently due to implementation difficulties, cf. this
comment in HalfOuterJoinNode.LOJ_reorderable.

// It is much easier to do LOJ reordering if there is no ROJ.
// However, we ran into some problem downstream when we transform an ROJ
// into LOJ -- transformOuterJoin() didn't expect ROJ to be transformed
// into LOJ alread.  So, we skip optimizing ROJ at the moment.

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