[jira] [Created] (SPARK-39061) Incorrect results or NPE when using Inline function against an array of dynamically created structs

["Bruce Robbins (Jira)" <ji...@apache.org>]

Bruce Robbins created SPARK-39061:
-------------------------------------

             Summary: Incorrect results or NPE when using Inline function against an array of dynamically created structs
                 Key: SPARK-39061
                 URL: https://issues.apache.org/jira/browse/SPARK-39061
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 3.2.1, 3.1.3, 3.3.0, 3.4.0
            Reporter: Bruce Robbins


The following query returns incorrect results:
{noformat}
spark-sql> select inline(array(named_struct('a', 1, 'b', 2), null));
1	2
-1	-1
Time taken: 4.053 seconds, Fetched 2 row(s)
spark-sql>
{noformat}
In Hive, the last row is {{NULL, NULL}}:
{noformat}
Beeline version 2.3.9 by Apache Hive
0: jdbc:hive2://localhost:10000> select inline(array(named_struct('a', 1, 'b', 2), null));
+-------+-------+
|   a   |   b   |
+-------+-------+
| 1     | 2     |
| NULL  | NULL  |
+-------+-------+
2 rows selected (1.355 seconds)
0: jdbc:hive2://localhost:10000> 
{noformat}
If the struct has string fields, you get a {{NullPointerException}}:
{noformat}
spark-sql> select inline(array(named_struct('a', '1', 'b', '2'), null));
22/04/28 16:51:54 ERROR Executor: Exception in task 0.0 in stage 2.0 (TID 2)
java.lang.NullPointerException: null
	at org.apache.spark.sql.catalyst.expressions.codegen.UnsafeWriter.write(UnsafeWriter.java:110) ~[spark-catalyst_2.12-3.4.0-SNAPSHOT.jar:3.4.0-SNAPSHOT]
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage1.generate_doConsume_0$(Unknown Source) ~[?:?]
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage1.processNext(Unknown Source) ~[?:?]
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43) ~[spark-sql_2.12-3.4.0-SNAPSHOT.jar:3.4.0-SNAPSHOT]
{noformat}
(Note: In Spark 3.1.3, both examples result in NPE).

You can work around the issue by casting the null entry of the array:
{noformat}
spark-sql> select inline(array(named_struct('a', 1, 'b', 2), cast(null as struct<a:int, b:int>)));
1	2
NULL	NULL
Time taken: 0.068 seconds, Fetched 2 row(s)
spark-sql>
{noformat}
(Note: In Spark 3.1.3, the above workaround does not work).

As far as I can tell, this issue only happens with arrays of structs where the structs are created in an inline table or in a projection.

The fields of the struct are not getting set to {{nullable = true}} when there is no example in the array where the field is set to {{null}}. As a result, {{GenerateUnsafeProjection.createCode}} generates bad code: it has no code to create a row of null columns, so it just creates a row from variables set with default values.



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