maropu commented on a change in pull request #32014:
URL: https://github.com/apache/spark/pull/32014#discussion_r605628437
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/CostBasedJoinReorder.scala
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@@ -349,11 +349,14 @@ object JoinReorderDP extends PredicateHelper with Logging
{
}
def betterThan(other: JoinPlan, conf: SQLConf): Boolean = {
- val thisCost = BigDecimal(this.planCost.card) *
conf.joinReorderCardWeight +
- BigDecimal(this.planCost.size) * (1 - conf.joinReorderCardWeight)
- val otherCost = BigDecimal(other.planCost.card) *
conf.joinReorderCardWeight +
- BigDecimal(other.planCost.size) * (1 - conf.joinReorderCardWeight)
- thisCost < otherCost
+ if (other.planCost.card == 0 || other.planCost.size == 0) {
+ false
+ } else {
Review comment:
How about leaving some comments about why we need to use relative values
here?
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