Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/13906#discussion_r68837197
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -1053,6 +1055,49 @@ object PruneFilters extends Rule[LogicalPlan] with
PredicateHelper {
}
/**
+ * Collapse plans consisting all empty local relations generated by
[[PruneFilters]].
+ * Note that the ObjectProducer/Consumer and direct aggregations are the
exceptions.
+ * {{{
+ * SELECT a, b FROM t WHERE 1=0 GROUP BY a, b ORDER BY a, b ==> empty
result
+ * SELECT SUM(a) FROM t WHERE 1=0 GROUP BY a HAVING COUNT(*)>1 ORDER BY
a (Not optimized)
+ * }}}
+ */
+object CollapseEmptyPlan extends Rule[LogicalPlan] with PredicateHelper {
--- End diff --
can you actually move this into a separate file? the optimizer is becoming
too large and I want to break it apart soon. No point adding new things in this
file.
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