Github user chenghao-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/1795#discussion_r15853348
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -121,6 +122,51 @@ class Analyzer(catalog: Catalog, registry:
FunctionRegistry, caseSensitive: Bool
}
/**
+ * In many dialects of SQL is it valid to sort by attributes that are
not present in the SELECT
+ * clause. This rule detects such queries and adds the required
attributes to the original
+ * projection, so that they will be available during sorting. Another
projection is added to
+ * remove these attributes after sorting.
+ */
+ object ResolveSortReferences extends Rule[LogicalPlan] {
+ def apply(plan: LogicalPlan): LogicalPlan = plan transformUp {
+ case s@Sort(ordering, p@Project(projectList, child)) if !s.resolved
&& p.resolved =>
+ val unresolved = ordering.flatMap(_.collect { case
UnresolvedAttribute(name) => name})
+ val resolved = unresolved.flatMap(child.resolveChildren)
+ val requiredAttributes = resolved.collect { case a: Attribute => a
}.toSet
+
+ val missingInProject = requiredAttributes -- p.output
+ if (missingInProject.nonEmpty) {
+ // Add missing attributes and then project them away after the
sort.
+ Project(projectList,
+ Sort(ordering,
+ Project(projectList ++ missingInProject, child)))
+ } else {
+ s // Nothing we can do here. Return original plan.
+ }
+ case s@Sort(ordering, a@Aggregate(grouping, aggs, child)) if
!s.resolved && a.resolved =>
+ val unresolved = ordering.flatMap(_.collect { case
UnresolvedAttribute(name) => name})
--- End diff --
Space before `}`
---
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.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
