From 67bd8e3c217a80c3117a6e3853aa60fe13d08c91 Mon Sep 17 00:00:00 2001
From: Yin Huai <huai@cse.ohio-state.edu>
Date: Sat, 2 Aug 2014 13:16:41 -0700
Subject: [PATCH] [SQL] Set outputPartitioning of BroadcastHashJoin correctly.
I think we will not generate the plan triggering this bug at this moment. But, let me explain it...
Right now, we are using `left.outputPartitioning` as the `outputPartitioning` of a `BroadcastHashJoin`. We may have a wrong physical plan for cases like...
```sql
SELECT l.key, count(*)
FROM (SELECT key, count(*) as cnt
FROM src
GROUP BY key) l // This is buildPlan
JOIN r // This is the streamedPlan
ON (l.cnt = r.value)
GROUP BY l.key
```
Let's say we have a `BroadcastHashJoin` on `l` and `r`. For this case, we will pick `l`'s `outputPartitioning` for the `outputPartitioning`of the `BroadcastHashJoin` on `l` and `r`. Also, because the last `GROUP BY` is using `l.key` as the key, we will not introduce an `Exchange` for this aggregation. However, `r`'s outputPartitioning may not match the required distribution of the last `GROUP BY` and we fail to group data correctly.
JIRA is being reindexed. I will create a JIRA ticket once it is back online.
Author: Yin Huai <huai@cse.ohio-state.edu>
Closes #1735 from yhuai/BroadcastHashJoin and squashes the following commits:
96d9cb3 [Yin Huai] Set outputPartitioning correctly.
---
.../src/main/scala/org/apache/spark/sql/execution/joins.scala | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins.scala
index cc138c7499..51bb615307 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins.scala
@@ -405,8 +405,7 @@ case class BroadcastHashJoin(
left: SparkPlan,
right: SparkPlan) extends BinaryNode with HashJoin {
-
- override def outputPartitioning: Partitioning = left.outputPartitioning
+ override def outputPartitioning: Partitioning = streamedPlan.outputPartitioning
override def requiredChildDistribution =
UnspecifiedDistribution :: UnspecifiedDistribution :: Nil
--
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