maropu commented on a change in pull request #26978: [SPARK-29721][SQL] Prune
unnecessary nested fields from Generate without Project
URL: https://github.com/apache/spark/pull/26978#discussion_r366155405
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -597,31 +597,24 @@ object ColumnPruning extends Rule[LogicalPlan] {
s.copy(child = prunedChild(child, s.references))
// prune unrequired references
- case p @ Project(_, g: Generate) if p.references != g.outputSet =>
- val requiredAttrs = p.references -- g.producedAttributes ++
g.generator.references
- val newChild = prunedChild(g.child, requiredAttrs)
- val unrequired = g.generator.references -- p.references
- val unrequiredIndices = newChild.output.zipWithIndex.filter(t =>
unrequired.contains(t._1))
- .map(_._2)
- p.copy(child = g.copy(child = newChild, unrequiredChildIndex =
unrequiredIndices))
-
- // prune unrequired nested fields
- case p @ Project(projectList, g: Generate) if
SQLConf.get.nestedPruningOnExpressions &&
- NestedColumnAliasing.canPruneGenerator(g.generator) =>
- NestedColumnAliasing.getAliasSubMap(projectList ++
g.generator.children).map {
- case (nestedFieldToAlias, attrToAliases) =>
- val newGenerator = g.generator.transform {
- case f: ExtractValue if nestedFieldToAlias.contains(f) =>
- nestedFieldToAlias(f).toAttribute
- }.asInstanceOf[Generator]
-
- // Defer updating `Generate.unrequiredChildIndex` to next round of
`ColumnPruning`.
- val newGenerate = g.copy(generator = newGenerator)
-
- val newChild =
NestedColumnAliasing.replaceChildrenWithAliases(newGenerate, attrToAliases)
-
- Project(NestedColumnAliasing.getNewProjectList(projectList,
nestedFieldToAlias), newChild)
- }.getOrElse(p)
+ case p @ Project(_, g: Generate) =>
+ val currP = if (p.references != g.outputSet) {
+ val requiredAttrs = p.references -- g.producedAttributes ++
g.generator.references
+ val newChild = prunedChild(g.child, requiredAttrs)
+ val unrequired = g.generator.references -- p.references
+ val unrequiredIndices = newChild.output.zipWithIndex.filter(t =>
unrequired.contains(t._1))
+ .map(_._2)
+ p.copy(child = g.copy(child = newChild, unrequiredChildIndex =
unrequiredIndices))
+ } else {
+ p
+ }
+ // If we can prune nested column on Project + Generate, do it now.
+ // Otherwise by transforming down to Generate, it could be pruned
individually,
+ // and causes nested column on top Project unable to resolve.
+ GeneratorNestedColumnAliasing.unapply(currP).getOrElse(currP)
Review comment:
Ah, I see.
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