Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/3778#discussion_r23123061
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -312,9 +309,26 @@ object BooleanSimplification extends Rule[LogicalPlan]
with PredicateHelper {
case (l, Literal(true, BooleanType)) => l
case (Literal(false, BooleanType), _) => Literal(false)
case (_, Literal(false, BooleanType)) => Literal(false)
- // a && a && a ... => a
- case _ if splitConjunctivePredicates(and).distinct.size == 1 =>
left
- case _ => and
+ // a && a => a
+ case (l, r) if l fastEquals r => l
+ case (_, _) =>
+ val lhsSet = splitDisjunctivePredicates(left).toSet
--- End diff --
I know this has been merged, but can you submit another PR to add comments
explaining how this works? I'm afraid this block of code is beyond a normal
engineer's capability to understand without spending hours staring at it.
Thanks.
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