wangyum commented on a change in pull request #31691:
URL: https://github.com/apache/spark/pull/31691#discussion_r585209573
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -613,6 +613,15 @@ object LimitPushDown extends Rule[LogicalPlan] {
case _ => join
}
LocalLimit(exp, newJoin)
+
+ case LocalLimit(limitExpr @ IntegerLiteral(limitVal),
+ window @ Window(Seq(Alias(WindowExpression(_: RankLike | _: RowNumber,
+ WindowSpecDefinition(Nil, orderSpec,
+ SpecifiedWindowFrame(RowFrame, UnboundedPreceding,
CurrentRow))), _)), _, _, child))
+ if child.maxRows.forall( _ > limitVal) =>
+ LocalLimit(
+ limitExpr = limitExpr,
+ child = window.copy(child = Limit(limitExpr, Sort(orderSpec, true,
child))))
Review comment:
The current logic is sort first and then limit:
```
== Physical Plan ==
AdaptiveSparkPlan isFinalPlan=false
+- Window [row_number() windowspecdefinition(a#10L ASC NULLS FIRST, b#11L
ASC NULLS FIRST, specifiedwindowframe(RowFrame, unboundedpreceding$(),
currentrow$())) AS rowId#8], [a#10L ASC NULLS FIRST, b#11L ASC NULLS FIRST]
+- TakeOrderedAndProject(limit=5, orderBy=[a#10L ASC NULLS FIRST,b#11L
ASC NULLS FIRST], output=[a#10L,b#11L])
+- FileScan parquet default.t1[a#10L,b#11L] Batched: true,
DataFilters: [], Format: Parquet, Location: InMemoryFileIndex(1
paths)[file:/Users/yumwang/opensource/spark/spark-warehouse/org.apache.spark....,
PartitionFilters: [], PushedFilters: [], ReadSchema: struct<a:bigint,b:bigint>
```
If remove sort. The logic is limit first and then sort:
```
== Physical Plan ==
AdaptiveSparkPlan isFinalPlan=false
+- Window [row_number() windowspecdefinition(a#10L ASC NULLS FIRST, b#11L
ASC NULLS FIRST, specifiedwindowframe(RowFrame, unboundedpreceding$(),
currentrow$())) AS rowId#8], [a#10L ASC NULLS FIRST, b#11L ASC NULLS FIRST]
+- Sort [a#10L ASC NULLS FIRST, b#11L ASC NULLS FIRST], false, 0
+- GlobalLimit 5
+- Exchange SinglePartition, ENSURE_REQUIREMENTS, [id=#30]
+- LocalLimit 5
+- FileScan parquet default.t1[a#10L,b#11L] Batched: true,
DataFilters: [], Format: Parquet, Location: InMemoryFileIndex(1
paths)[file:/Users/yumwang/opensource/spark/spark-warehouse/org.apache.spark....,
PartitionFilters: [], PushedFilters: [], ReadSchema: struct<a:bigint,b:bigint>
```
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