Github user chenghao-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/482#discussion_r12265606
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -87,6 +88,56 @@ object ColumnPruning extends Rule[LogicalPlan] {
/**
* Replaces [[catalyst.expressions.Expression Expressions]] that can be
statically evaluated with
+ * equivalent [[catalyst.expressions.Literal Literal]] values. This rule
is more specific with
+ * Null value propagation from bottom to top of the expression tree.
+ */
+object NullPropagation extends Rule[LogicalPlan] {
+ def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+ case q: LogicalPlan => q transformExpressionsUp {
+ // Skip redundant folding of literals.
+ case l: Literal => l
--- End diff --
The same as the rule ConstantFolding, NullPropagation won't do any
transformation for Literal.
---
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.
---
