Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/17148#discussion_r104491614
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/statsEstimation/FilterEstimation.scala
---
@@ -90,32 +95,43 @@ case class FilterEstimation(plan: Filter, catalystConf:
CatalystConf) extends Lo
def calculateFilterSelectivity(condition: Expression, update: Boolean =
true): Option[Double] = {
condition match {
case And(cond1, cond2) =>
- // For ease of debugging, we compute percent1 and percent2 in 2
statements.
- val percent1 = calculateFilterSelectivity(cond1, update)
- val percent2 = calculateFilterSelectivity(cond2, update)
- (percent1, percent2) match {
- case (Some(p1), Some(p2)) => Some(p1 * p2)
- case (Some(p1), None) => Some(p1)
- case (None, Some(p2)) => Some(p2)
- case (None, None) => None
- }
+ val percent1 = calculateFilterSelectivity(cond1,
update).getOrElse(1.0)
+ val percent2 = calculateFilterSelectivity(cond2,
update).getOrElse(1.0)
+ Some(percent1 * percent2)
case Or(cond1, cond2) =>
- // For ease of debugging, we compute percent1 and percent2 in 2
statements.
- val percent1 = calculateFilterSelectivity(cond1, update = false)
- val percent2 = calculateFilterSelectivity(cond2, update = false)
- (percent1, percent2) match {
- case (Some(p1), Some(p2)) => Some(math.min(1.0, p1 + p2 - (p1 *
p2)))
- case (Some(p1), None) => Some(1.0)
- case (None, Some(p2)) => Some(1.0)
- case (None, None) => None
+ val percent1 = calculateFilterSelectivity(cond1, update =
false).getOrElse(1.0)
+ val percent2 = calculateFilterSelectivity(cond2, update =
false).getOrElse(1.0)
+ Some(percent1 + percent2 - (percent1 * percent2))
+
+ // For AND and OR conditions, we will estimate conservatively if one
of two
+ // components is not supported, e.g. suppose c1 is not supported,
+ // then p(And(c1, c2)) = p(c2), and p(Or(c1, c2)) = 1.0.
+ // But once they are wrapped in NOT condition, then after 1 - p, it
becomes
+ // under-estimation. So in these cases, we consider them as
unsupported.
+ case Not(And(cond1, cond2)) =>
--- End diff --
If `cond1` is also `And`, and is over-estimated, then we get a problem here.
We should not handle compound `Not` at all, just call
`calculateSingleCondition` for `Not`.
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