GitHub user maropu opened a pull request:
https://github.com/apache/spark/pull/21148
[SPARK-24079][SQL] Update the nullability of Join output based on inferred
predicates
## What changes were proposed in this pull request?
This pr added code to update the nullability of `Join.output` based on
inferred predicates in `InferFiltersFromConstraints`. In the master, a logical
`Join` node does not respect the nullability that the optimizer rule
`InferFiltersFromConstraints` might change when inferred predicates have
`IsNotNull`,
e.g.,
```
scala> val df1 = Seq((Some(1), Some(2))).toDF("k", "v0")
scala> val df2 = Seq((Some(1), Some(3))).toDF("k", "v1")
scala> val joinedDf = df1.join(df2, df1("k") === df2("k"), "inner")
scala> joinedDf.explain
== Physical Plan ==
*(2) BroadcastHashJoin [k#83], [k#92], Inner, BuildRight
:- *(2) Project [_1#80 AS k#83, _2#81 AS v0#84]
: +- *(2) Filter isnotnull(_1#80)
: +- LocalTableScan [_1#80, _2#81]
+- BroadcastExchange HashedRelationBroadcastMode(List(cast(input[0, int,
true] as bigint)))
+- *(1) Project [_1#89 AS k#92, _2#90 AS v1#93]
+- *(1) Filter isnotnull(_1#89)
+- LocalTableScan [_1#89, _2#90]
scala> joinedDf.queryExecution.optimizedPlan.output.map(_.nullable)
res15: Seq[Boolean] = List(true, true, true, true)
```
But, these `nullable` values should be:
```
scala> joinedDf.queryExecution.optimizedPlan.output.map(_.nullable)
res15: Seq[Boolean] = List(false, true, false, true)
```
This ticket comes from the previous discussion:
https://github.com/apache/spark/pull/18576#pullrequestreview-107585997
## How was this patch tested?
Added tests in `UpdateNullabilityInAttributeReferencesSuite`.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/maropu/spark UpdateJoinNullability
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/21148.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #21148
----
commit 240ae7a976f03ce58bcdeed34f8022ebfea23a4c
Author: Takeshi Yamamuro <yamamuro@...>
Date: 2018-04-02T08:07:52Z
Fix
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