cloud-fan commented on a change in pull request #33930:
URL: https://github.com/apache/spark/pull/33930#discussion_r705130603
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
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@@ -290,6 +290,21 @@ object OptimizeIn extends Rule[LogicalPlan] {
* 4. Removes `Not` operator.
*/
object BooleanSimplification extends Rule[LogicalPlan] with PredicateHelper {
+ // Given argument x, return true if expression Not(x) can be simplified
+ // E.g. when x == Not(y), Not(x) == Not(Not(y)) == y
+ // For the case of x = EqualTo(a, b), recursively check each child expression
+ // Extra nullable check is required for EqualNullSafe because
+ // Not(EqualNullSafe(x, null)) is different from EqualNullSafe(x, Not(null))
+ private def canSimplifyNot(x: Expression): Boolean = x match {
+ case Literal(_, BooleanType) | Literal(_, NullType) => true
+ case _: Not | _: IsNull | _: IsNotNull | _: And | _: Or => true
+ case _: GreaterThan | _: GreaterThanOrEqual | _: LessThan | _:
LessThanOrEqual => true
+ case EqualTo(a, b) if canSimplifyNot(a) || canSimplifyNot(b) => true
Review comment:
I'm not sure we should recursive into `EqualTo`. For example:
`Not(EqualTo(a, EqualTo(b, EqualTo(c, d))))`, if `d` is optimizable, we will
turn it into `EqualTo(Not(a), EqualTo(Not(b), EqualTo(Not(c), optimized_d)))`.
We need to evaluate `Not` more times which is a perf degradation.
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