[DERBY-4742] Make outer join reordering work for right outer joins

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 10.0.2.0, 10.0.2.1, 10.1.1.0, 10.1.2.1, 10.1.3.1, 10.2.1.6, 10.2.2.0, 10.3.1.4, 10.3.2.1, 10.3.3.0, 10.4.1.3, 10.4.2.0, 10.5.1.1, 10.5.2.0, 10.5.3.0, 10.6.1.0
• Component/s: SQL
• Labels: derby_triage10_10
• Urgency: Normal
• Assignee: Unassigned
• Reporter: Dag H. Wanvik
• Created: 12/Jul/10 18:45
• Updated: 28/Sep/12 18:32

Description

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.

Issue Links

• is related to: DERBY-4471 Left outer join reassociation rewrite gives wrong result