bersprockets opened a new pull request, #36903:
URL: https://github.com/apache/spark/pull/36903
### What changes were proposed in this pull request?
Change `Inline.eval` to return a row of null values rather than a null row
in the case of a null input struct.
### Why are the changes needed?
Consider the following query:
```
set spark.sql.codegen.wholeStage=false;
select inline(array(named_struct('a', 1, 'b', 2), null));
```
This query fails with a `NullPointerException`:
```
22/06/16 15:10:06 ERROR Executor: Exception in task 0.0 in stage 0.0 (TID 0)
java.lang.NullPointerException
at
org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown
Source)
at
org.apache.spark.sql.execution.GenerateExec.$anonfun$doExecute$11(GenerateExec.scala:122)
```
(In Spark 3.1.3, you don't need to set `spark.sql.codegen.wholeStage` to
false to reproduce the error, since Spark 3.1.3 has no codegen path for
`Inline`).
This query fails regardless of the setting of `spark.sql.codegen.wholeStage`:
```
val dfWide = (Seq((1))
.toDF("col0")
.selectExpr(Seq.tabulate(99)(x => s"$x as col${x + 1}"): _*))
val df = (dfWide
.selectExpr("*", "array(named_struct('a', 1, 'b', 2), null) as
struct_array"))
df.selectExpr("*", "inline(struct_array)").collect
```
It fails with
```
22/06/16 15:18:55 ERROR Executor: Exception in task 0.0 in stage 0.0 (TID
0)/ 1]
java.lang.NullPointerException
at
org.apache.spark.sql.catalyst.expressions.JoinedRow.isNullAt(JoinedRow.scala:80)
at
org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.writeFields_0_8$(Unknown
Source)
```
When `Inline.eval` returns a null row in the collection, GenerateExec gets a
NullPointerException either when joining the null row with required child
output, or projecting the null row.
This PR avoids producing the null row and produces a row of null values
instead:
```
spark-sql> set spark.sql.codegen.wholeStage=false;
spark.sql.codegen.wholeStage false
Time taken: 3.095 seconds, Fetched 1 row(s)
spark-sql> select inline(array(named_struct('a', 1, 'b', 2), null));
1 2
NULL NULL
Time taken: 1.214 seconds, Fetched 2 row(s)
spark-sql>
```
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
New unit test.
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