n-young-db commented on code in PR #46974:
URL: https://github.com/apache/spark/pull/46974#discussion_r1644727900
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/InsertMapSortInGroupingExpressions.scala:
##########
@@ -17,29 +17,41 @@
package org.apache.spark.sql.catalyst.optimizer
-import org.apache.spark.sql.catalyst.expressions.MapSort
-import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, LogicalPlan}
+import org.apache.spark.sql.catalyst.expressions.{Alias, AliasHelper, MapSort}
+import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, LogicalPlan,
Project}
import org.apache.spark.sql.catalyst.rules.Rule
import org.apache.spark.sql.catalyst.trees.TreePattern.AGGREGATE
import org.apache.spark.sql.types.MapType
/**
- * Adds MapSort to group expressions containing map columns, as the key/value
paris need to be
- * in the correct order before grouping:
+ * Adds MapSort to group expressions containing map columns by pushing down
the projection,
+ * as the key/value pairs need to be in the correct order before grouping:
* SELECT COUNT(*) FROM TABLE GROUP BY map_column =>
- * SELECT COUNT(*) FROM TABLE GROUP BY map_sort(map_column)
+ * SELECT COUNT(*) FROM (SELECT map_sort(map_column) as map_sorted) GROUP BY
map_sorted
+ *
+ * SELECT map_column FROM TABLE GROUP BY map_column =>
+ * SELECT map_sorted FROM (SELECT map_sort(map_column) as map_sorted) GROUP BY
map_sorted
+ *
+ * We inject a new `Project` to ensure that we don't do recomputation, and so
that we can reference
+ * the newly sorted map column in the aggregate expressions list.
*/
-object InsertMapSortInGroupingExpressions extends Rule[LogicalPlan] {
+object InsertMapSortInGroupingExpressions extends Rule[LogicalPlan] with
AliasHelper {
override def apply(plan: LogicalPlan): LogicalPlan =
plan.transformWithPruning(
_.containsPattern(AGGREGATE), ruleId) {
- case a @ Aggregate(groupingExpr, _, _) =>
- val newGrouping = groupingExpr.map { expr =>
- if (!expr.isInstanceOf[MapSort] &&
expr.dataType.isInstanceOf[MapType]) {
- MapSort(expr)
- } else {
- expr
- }
- }
- a.copy(groupingExpressions = newGrouping)
+ case a @ Aggregate(groupingExpr, aggregateExpr, child) =>
+ val toSort = groupingExpr.filter( expr =>
+ !expr.isInstanceOf[MapSort] && expr.dataType.isInstanceOf[MapType]
+ )
+ val newChild = Project(toSort.map( expr =>
Review Comment:
We need to project the other, nonsorted columns, otherwise other attributes
will be dropped. Just need to add `child.output` to the Project
```
val toSort = groupingExpr.filter( expr =>
!expr.isInstanceOf[MapSort] && expr.dataType.isInstanceOf[MapType]
)
val newChild = Project(toSort.map( expr =>
Alias(MapSort(expr), s"map_sorted_${expr.prettyName}")()
) ++ child.output, child)
```
and then ColumnPruning will take care of the rest
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