[GitHub] [spark] cloud-fan commented on a diff in pull request #38558: [SPARK-41048][SQL] Improve output partitioning and ordering with AQE cache

[GitBox <gi...@apache.org>]

cloud-fan commented on code in PR #38558:
URL: https://github.com/apache/spark/pull/38558#discussion_r1016656445


##########
sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/AdaptiveSparkPlanExec.scala:
##########
@@ -209,6 +209,19 @@ case class AdaptiveSparkPlanExec(
 
   override def output: Seq[Attribute] = inputPlan.output
 
+  // Try our best to give a stable output partitioning and ordering.

Review Comment:
   I'm trying to understand this "best effort". AFAIK, table cache is lazy. For a query that accesses a cached query the first time, the cached query is not executed yet so we don't know the output partitioning/ordering and can't optimize out shuffles. But when the cached query is accessed the next time, it's already executed and we know the output partitioning/ordering.



-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org