Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/11815#discussion_r56618306
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -618,9 +622,33 @@ class Analyzer(
* clause. This rule detects such queries and adds the required
attributes to the original
* projection, so that they will be available during sorting. Another
projection is added to
* remove these attributes after sorting.
+ *
+ * This rule also resolves the position number in Sort references. This
support is introduced
+ * in Spark 2.0. Before Spark 2.0, the integers in Order By has no
effect on output sorting.
*/
object ResolveSortReferences extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan resolveOperators {
+ // Replace the index with the related attribute for ORDER BY
+ // which is a 1-base position of the projection list.
+ case s @ Sort(orders, global, child)
+ if child.resolved && orders.exists(o =>
IntegerIndex.unapply(o.child).nonEmpty) =>
+ val newOrders = orders map {
+ case s @ SortOrder(IntegerIndex(index), direction) =>
+ if (index > 0 && index <= child.output.size &&
conf.orderByOrdinal) {
+ SortOrder(child.output(index - 1), direction)
+ } else if (!conf.orderByOrdinal) {
+ failAnalysis(
+ "Integer in the Order/Sort By clause is not allowed " +
--- End diff --
i'd say if the flag is set to false, we should just ignore the foldable
constants.
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