cloud-fan commented on code in PR #37320:
URL: https://github.com/apache/spark/pull/37320#discussion_r935061143
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sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/V2ScanRelationPushDown.scala:
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@@ -410,12 +413,21 @@ object V2ScanRelationPushDown extends Rule[LogicalPlan]
with PredicateHelper {
case s @ Sort(order, _, operation @ ScanOperation(project, filter,
sHolder: ScanBuilderHolder))
// Without building the Scan, we do not know the resulting column
names after aggregate
// push-down, and thus can't push down Top-N which needs to know the
ordering column names.
- // TODO: we can support simple cases like GROUP BY columns directly
and ORDER BY the same
- // columns, which we know the resulting column names: the
original table columns.
- if sHolder.pushedAggregate.isEmpty && filter.isEmpty &&
+ // In particular, we push down the simple cases like GROUP BY
expressions directly and
+ // ORDER BY the same expressions, which we know the original table
columns.
+ if filter.isEmpty &&
CollapseProject.canCollapseExpressions(order, project, alwaysInline
= true) =>
val aliasMap = getAliasMap(project)
- val newOrder = order.map(replaceAlias(_,
aliasMap)).asInstanceOf[Seq[SortOrder]]
+ val aliasReplacedOrder = order.map(replaceAlias(_, aliasMap))
+ val newOrder = if (sHolder.pushedAggregate.isDefined) {
+ aliasReplacedOrder.map {
Review Comment:
let's add some comments here.
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