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https://issues.apache.org/jira/browse/FLINK-2871?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15097058#comment-15097058
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ASF GitHub Bot commented on FLINK-2871:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1469#discussion_r49655529
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/operators/hash/NonReusingBuildFirstHashJoinIterator.java
---
@@ -144,13 +148,20 @@ public final boolean
callWithNextKey(FlatJoinFunction<V1, V2, O> matchFunction,
// only single pair matches
matchFunction.join(nextBuildSideRecord,
probeRecord, collector);
}
- }
- else if(joinWithEmptyBuildSide) {
- // build side is empty, join with null
- final V2 probeRecord =
this.hashJoin.getCurrentProbeRecord();
+ } else {
+ if (probeSideOuterJoin && probeRecord != null
&& nextBuildSideRecord == null) {
--- End diff --
Can you add a few comments in this `else` branch?
Please do the same for the other adapted HashJoinIterators.
> Add OuterJoin strategy with HashTable on outer side
> ---------------------------------------------------
>
> Key: FLINK-2871
> URL: https://issues.apache.org/jira/browse/FLINK-2871
> Project: Flink
> Issue Type: New Feature
> Components: Local Runtime, Optimizer
> Affects Versions: 0.10.0
> Reporter: Fabian Hueske
> Assignee: Chengxiang Li
> Priority: Minor
>
> Outer joins are currently supported with two local execution strategies:
> - sort-merge join
> - hash join where the hash table is built on the inner side. Hence, this
> strategy is only supported for left and right outer joins.
> In order to support hash-tables on the outer side, we need a special hash
> table implementation that gives access to all records which have not been
> accessed during the probe phase.
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