Github user dongjoon-hyun commented on a diff in the pull request:
https://github.com/apache/spark/pull/12719#discussion_r62808356
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -618,6 +619,48 @@ object NullPropagation extends Rule[LogicalPlan] {
}
/**
+ * Propagate foldable expressions:
+ * Replace attributes with aliases of the original foldable expressions if
possible.
+ * Other optimizations will take advantage of the propagated foldable
expressions.
+ *
+ * {{{
+ * SELECT 1.0 x, 'abc' y, Now() z ORDER BY x, y, 3
+ * ==> SELECT 1.0 x, 'abc' y, Now() z ORDER BY 1.0, 'abc', Now()
+ * }}}
+ */
+object FoldablePropagation extends Rule[LogicalPlan] {
+ def apply(plan: LogicalPlan): LogicalPlan = {
+ val foldableExprSet = ExpressionSet(plan.flatMap {
+ case Project(projectList, _) => projectList.collect {
+ case a: Alias if a.resolved && a.child.foldable => a
+ }
+ case _ => Nil
+ })
+
+ if (foldableExprSet.isEmpty) {
+ plan
+ } else {
+ val foldableMap =
AttributeMap(foldableExprSet.toSeq.map(_.asInstanceOf[Alias])
+ .map(a => (a.toAttribute, a.child)))
--- End diff --
Sorry, actually, I didn't investigate all kinds of Plan exhaustively at
that time.
I focused on only `Project`, `Filter`, `Aggregate`, and `Sort`.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
