Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/5717#discussion_r36238964
--- Diff: sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala ---
@@ -152,16 +149,14 @@ class JoinSuite extends QueryTest with
BeforeAndAfterEach {
ctx.cacheManager.clearCache()
ctx.sql("CACHE TABLE testData")
- val SORTMERGEJOIN_ENABLED: Boolean = ctx.conf.sortMergeJoinEnabled
Seq(
- ("SELECT * FROM testData LEFT JOIN testData2 ON key = a",
classOf[ShuffledHashOuterJoin]),
+ ("SELECT * FROM testData LEFT JOIN testData2 ON key = a",
classOf[SortMergeJoin]),
("SELECT * FROM testData RIGHT JOIN testData2 ON key = a where key =
2",
- classOf[BroadcastHashOuterJoin]),
--- End diff --
It looks like this patch causes us to plan SortMergeJoin for outer joins
that are capable of using BroadcastHashOuterJoin, which seems like it could
lead to performance issues by triggering unnecessary shuffling of the large
table.
As a result, I think that we should not change the broadcast-enabled half
of the test, but, rather, should update the broadcast-disabled half to test
both the sort-merge-join enabled and sort-merge-join-disabled configurations.
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