Github user sirpkt commented on a diff in the pull request:
https://github.com/apache/tajo/pull/379#discussion_r24469183
--- Diff:
tajo-plan/src/main/java/org/apache/tajo/plan/joinorder/GreedyHeuristicJoinOrderAlgorithm.java
---
@@ -57,17 +54,69 @@ public FoundJoinOrder findBestOrder(LogicalPlan plan,
LogicalPlan.QueryBlock blo
JoinEdge bestPair;
while (remainRelations.size() > 1) {
+ Set<LogicalNode> checkingRelations = new
LinkedHashSet<LogicalNode>();
+
+ for (LogicalNode relation : remainRelations) {
+ Collection <String> relationStrings =
PlannerUtil.getRelationLineageWithinQueryBlock(plan, relation);
+ List<JoinEdge> joinEdges = new ArrayList<JoinEdge>();
+ String relationCollection =
TUtil.collectionToString(relationStrings, ",");
+ List<JoinEdge> joinEdgesForGiven =
joinGraph.getIncomingEdges(relationCollection);
+ if (joinEdgesForGiven != null) {
+ joinEdges.addAll(joinEdgesForGiven);
+ }
+ for (String relationString: relationStrings) {
+ joinEdgesForGiven = joinGraph.getIncomingEdges(relationString);
+ if (joinEdgesForGiven != null) {
+ joinEdges.addAll(joinEdgesForGiven);
+ }
+ }
+
+ // check if the relation is the last piece of outer join
+ boolean endInnerRelation = false;
+ for (JoinEdge joinEdge: joinEdges) {
--- End diff --
Actually, I thought that the order of JoinEdges in joinEdges list does not
matter.
Since the given relation is the right relation for all the JoinEdges,
I just check the existence of JoinEdge that is outer join.
And, in my thought, the result does not vary regardless of the order of
JoinEdge's occurrence.
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