Github user maropu commented on a diff in the pull request:
https://github.com/apache/spark/pull/22219#discussion_r214825542
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/SparkPlan.scala ---
@@ -329,17 +337,26 @@ abstract class SparkPlan extends QueryPlan[SparkPlan]
with Logging with Serializ
*
* This is modeled after `RDD.take` but never runs any job locally on
the driver.
*/
- def executeTake(n: Int): Array[InternalRow] = {
+ def executeTake(n: Int): Array[InternalRow] =
executeTakeSeqView(n)._2.force
+
+ /**
+ * Runs this query returning the tuple of the row count and the SeqView
of first `n` rows.
+ *
+ * This is modeled to execute decodeUnsafeRows lazily to reduce peak
memory usage of
+ * decoding rows. Only compressed byte arrays consume memory after
return.
+ */
+ private[spark] def executeTakeSeqView(
--- End diff --
For example, `collectCountAndSeqView` and `executeTakeSeqView` depend on
each other? If no, please split them into separate PRs.
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