huaxingao commented on a change in pull request #34291:
URL: https://github.com/apache/spark/pull/34291#discussion_r729982797
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/V2ScanRelationPushDown.scala
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@@ -225,6 +226,31 @@ object V2ScanRelationPushDown extends Rule[LogicalPlan]
with PredicateHelper {
withProjection
}
+ def applyLimit(plan: LogicalPlan): LogicalPlan = plan.transform {
+ case globalLimit @ GlobalLimit(_, LocalLimit(limitExpr, child)) => child
match {
Review comment:
Technically, it's no problem to only match `LocalLimit`.
I looked the code, seems to me that the only case that we have `LocalLimit`
without `GlobalLimit` is when we push down `LocalLimit` beneath `UNION ALL` and
joins in this rule
https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala#L645.
I think we won't hit this case because `UNION ALL` and joins are not pushed
down for data source.
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