Josh Rosen created SPARK-42754:
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Summary: Spark 3.4 history server's SQL tab incorrectly groups SQL
executions when replaying event logs from Spark 3.3 and earlier
Key: SPARK-42754
URL: https://issues.apache.org/jira/browse/SPARK-42754
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 3.4.0
Reporter: Josh Rosen
Attachments: example.png
In Spark 3.4.0 RC4, the Spark History Server's SQL tab incorrectly groups SQL
executions when replaying event logs generated by older Spark versions.
{*}Reproduction{*}:
{{In ./bin/spark-shell --conf spark.eventLog.enabled=true --conf
spark.eventLog.dir=eventlogs, run three non-nested SQL queries:}}
{code:java}
sql("select * from range(10)").collect()
sql("select * from range(20)").collect()
sql("select * from range(30)").collect(){code}
Exit the shell and use the Spark History Server to replay this UI.
In the SQL tab I expect to see three separate queries, but Spark 3.4's history
server incorrectly groups the second and third queries as nested queries of the
first (see attached screenshot).
{*}Root cause{*}:
[https://github.com/apache/spark/pull/39268] / SPARK-41752 added a new
*non-optional* {{rootExecutionId: Long}} field to the
SparkListenerSQLExecutionStart case class.
When JsonProtocol deserializes this event it uses the "ignore missing
properties" Jackson deserialization option, causing the {{rootExecutionField}}
to be initialized with a default value of {{{}0{}}}.
The value {{0}} is a legitimate execution ID, so in the deserialized event we
have no ability to distinguish between the absence of a value and a case where
all queries have the first query as the root.
*Proposed* {*}fix{*}:
I think we should change this field to be of type {{Option[Long]}} . I believe
this is a release blocker for Spark 3.4.0 because we cannot change the type of
this new field in a future release without breaking binary compatibility.
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