Github user mgaido91 commented on a diff in the pull request: https://github.com/apache/spark/pull/22630#discussion_r222956995 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegenExec.scala --- @@ -345,6 +345,27 @@ trait CodegenSupport extends SparkPlan { * don't require shouldStop() in the loop of producing rows. */ def needStopCheck: Boolean = parent.needStopCheck + + /** + * A sequence of checks which evaluate to true if the downstream Limit operators have not received + * enough records and reached the limit. If current node is a data producing node, it can leverage + * this information to stop producing data and complete the data flow earlier. Common data + * producing nodes are leaf nodes like Range and Scan, and blocking nodes like Sort and Aggregate. + * These checks should be put into the loop condition of the data producing loop. + */ + def limitNotReachedChecks: Seq[String] = parent.limitNotReachedChecks + + /** + * A helper method to generate the data producing loop condition according to the + * limit-not-reached checks. + */ + final def limitNotReachedCond: String = { + if (parent.limitNotReachedChecks.isEmpty) { + "" + } else { + parent.limitNotReachedChecks.mkString(" && ", " && ", "") --- End diff -- here we are assuming that this is going to be in and with an already existing condition. I don't see a case in which this may be used is a different context as of now, but what about just producing the conditions here and put the initial and outside of this? It may be easier to reuse this. WDYT?
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