Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/16245#discussion_r91886133
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
---
@@ -514,6 +514,25 @@ case class OptimizeCodegen(conf: CatalystConf) extends
Rule[LogicalPlan] {
/**
+ * Reorders the predicates in `Filter` so more expensive expressions like
UDF can evaluate later.
+ */
+object ReorderPredicatesInFilter extends Rule[LogicalPlan] with
PredicateHelper {
+ def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+ case Filter(pred, child) =>
+ // Reverses the expressions to get the suffix deterministic
expressions in the predicate.
+ // E.g., the original expressions are 'a > 1, rand(0), 'b > 2, 'c >
3.
+ // The reversed expressions are 'c > 3, 'b > 2, rand(0), 'a > 1.
+ // The suffix deterministic expressions are 'c > 3, 'b > 2.
+ val (deterministicExprs, others) =
splitConjunctivePredicates(pred).reverse
--- End diff --
the split is widely used in optimizer. i think i may rewrite this reverse
and span to alleviate performance concern.
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