ostronaut commented on code in PR #49144:
URL: https://github.com/apache/spark/pull/49144#discussion_r1904196842
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/InsertMapSortExpression.scala:
##########
@@ -77,15 +71,56 @@ object InsertMapSortInGroupingExpressions extends
Rule[LogicalPlan] {
}.asInstanceOf[NamedExpression]
}
val newChild = Project(child.output ++ exprToMapSort.values, child)
- val newAgg = Aggregate(newGroupingKeys, newAggregateExprs, newChild)
+ val newAgg = Aggregate(newGroupingKeys, newAggregateExprs, newChild,
hint)
newAgg -> agg.output.zip(newAgg.output)
}
}
+}
+
+/**
+ * Adds [[MapSort]] to [[RepartitionByExpression]] expressions containing map
columns,
+ * as the key/value pairs need to be in the correct order before
repartitioning:
+ *
+ * SELECT * FROM TABLE DISTRIBUTE BY map_column =>
+ * SELECT * FROM TABLE DISTRIBUTE BY map_sort(map_column)
+ */
+object InsertMapSortInRepartitionExpressions extends Rule[LogicalPlan] {
Review Comment:
initially i wanted to do the same, but logic for
`InsertMapSortInGroupingExpressions` and
`InsertMapSortInRepartitionExpressions` is quite different: Grouping produced
new output after applying the changes, while Repartition only updates existing
`RepartitionByExpression` by replacing `partitionExpressions`.
Also, there is a dependency between `InsertMapSortInGroupingExpressions` and
`PullOutGroupingExpressions`, as mentioned in [this
comment](https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala#L320).
For those reasons i decided to split them into separate Rules. But if you
think performance saving from reduced traverse will be significant, we can
combine those sure.
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