Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/1238#discussion_r14739228
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala
---
@@ -26,6 +26,17 @@ import org.apache.spark.sql.catalyst.trees
abstract class LogicalPlan extends QueryPlan[LogicalPlan] {
self: Product =>
+ protected class Estimates {
+ lazy val childrenEstimations = children.map(_.estimates)
+ lazy val cardinality: Long = childrenEstimations.map(_.cardinality).sum
+ lazy val sizeInBytes: Long = childrenEstimations.map(_.sizeInBytes).sum
--- End diff --
Yeah, but the sum could also wildly underestimate compared with a product
for many join cases. The 1 is only to prevent anything * 0 = 0 happening for
outer joins.
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