cloud-fan commented on a change in pull request #32885:
URL: https://github.com/apache/spark/pull/32885#discussion_r651019687
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/HashAggregateExec.scala
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@@ -73,7 +73,9 @@ case class HashAggregateExec(
// This is for testing. We force TungstenAggregationIterator to fall back to
the unsafe row hash
// map and/or the sort-based aggregation once it has processed a given
number of input rows.
private val testFallbackStartsAt: Option[(Int, Int)] = {
- sqlContext.getConf("spark.sql.TungstenAggregate.testFallbackStartsAt",
null) match {
+ Option(sqlContext).map { sc =>
Review comment:
This is a hidden bug. `SubqueryExpression` will be sent to the executor
side and build `Projection`, and be put in `EquivalentExpressions`, which needs
to call `canonicalized`.
This means, Spark may serialize and send `HashAggregateExec` to the executor
side, where `sqlContext` should be null.
It's hidden for a long time because `ScalarSubquery` didn't implement
`canonicalized`, so the bug is not triggered. However, it also means
`semanticHash` is wrong.
I think it only affects common subquery elimination, and shouldn't be a
serious bug.
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