cloud-fan commented on a change in pull request #34504:
URL: https://github.com/apache/spark/pull/34504#discussion_r755210674
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
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@@ -1548,6 +1548,31 @@ object PushPredicateThroughNonJoin extends
Rule[LogicalPlan] with PredicateHelpe
filter
}
+ case filter @ Filter(condition, w: Window) if w.partitionSpec.isEmpty =>
+ w.windowExpressions match {
+ case Seq(alias @ Alias(WindowExpression(_: RowNumber,
WindowSpecDefinition(Nil, orderSpec,
+ SpecifiedWindowFrame(RowFrame, UnboundedPreceding, CurrentRow))),
_)) =>
Review comment:
I think this optimization should also apply if there are more than one
window expressions. The algorithm should simply be
```
val limits = w.windowExpressions.map {
case row_number_func => calcuate the limit
case _ => none
}
val limit = limits.min
add limit + sort
```
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