Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/482#discussion_r12036482
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -91,10 +91,53 @@ object ColumnPruning extends Rule[LogicalPlan] {
*/
object ConstantFolding extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan transform {
- case q: LogicalPlan => q transformExpressionsDown {
+ case q: LogicalPlan => q transformExpressionsUp {
// Skip redundant folding of literals.
case l: Literal => l
+ // if it's foldable
case e if e.foldable => Literal(e.eval(null), e.dataType)
+ case e @ Count(Literal(null, _)) => Literal(null, e.dataType)
+ case e @ Sum(Literal(null, _)) => Literal(null, e.dataType)
+ case e @ Average(Literal(null, _)) => Literal(null, e.dataType)
+ case e @ IsNull(Literal(null, _)) => Literal(true, BooleanType)
+ case e @ IsNull(Literal(_, _)) => Literal(false, BooleanType)
+ case e @ IsNull(c @ Rand) => Literal(false, BooleanType)
+ case e @ IsNotNull(Literal(null, _)) => Literal(false, BooleanType)
+ case e @ IsNotNull(Literal(_, _)) => Literal(true, BooleanType)
+ case e @ IsNotNull(c @ Rand) => Literal(true, BooleanType)
+ case e @ GetItem(Literal(null, _), _) => Literal(null, e.dataType)
+ case e @ GetItem(_, Literal(null, _)) => Literal(null, e.dataType)
+ case e @ GetField(Literal(null, _), _) => Literal(null, e.dataType)
+ case e @ Coalesce(children) => {
+ val newChildren = children.filter(c => c match {
+ case Literal(null, _) => false
+ case _ => true
+ })
+ if(newChildren.length == null) {
--- End diff --
Can `.length == null`? Also, `transform` already does equality checking to
minimize GC churn, so I think its okay to just return a filtered version of the
children.
---
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 [email protected] or file a JIRA ticket
with INFRA.
---
