Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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3.2.1, 3.3.0, 3.4.0
Description
The following query returns incorrect results:
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>
In Hive, the last row is NULL, NULL:
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>
If the struct has string fields, you get a NullPointerException:
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]
You can work around the issue by casting the null entry of the array:
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>
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.
