Comment.

yhuai · yhuai · commit e38f264db244 · 2015-06-01T20:56:20.000-07:00
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
@@ -186,7 +186,8 @@ object ProjectCollapsing extends Rule[LogicalPlan] {
   }
 
   def apply(plan: LogicalPlan): LogicalPlan = plan transformUp {
-    // We only collapse these two
+    // We only collapse these two Projects if the child Project's expressions are all
+    // deterministic.
     case Project(projectList1, Project(projectList2, child))
       if !hasNondeterministic(projectList2) =>
       // Create a map of Aliases to their values from the child projection.

Original file line number	Diff line number	Diff line change
`@@ -186,7 +186,8 @@ object ProjectCollapsing extends Rule[LogicalPlan] {`
`186`	`186`	`}`
`187`	`187`
`188`	`188`	`def apply(plan: LogicalPlan): LogicalPlan = plan transformUp {`
`189`		`- // We only collapse these two`
	`189`	`+ // We only collapse these two Projects if the child Project's expressions are all`
	`190`	`+ // deterministic.`
`190`	`191`	`case Project(projectList1, Project(projectList2, child))`
`191`	`192`	`if !hasNondeterministic(projectList2) =>`
`192`	`193`	`// Create a map of Aliases to their values from the child projection.`