Github user codingjaguar commented on a diff in the pull request:
https://github.com/apache/spark/pull/10163#discussion_r47176854
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
---
@@ -252,6 +253,27 @@ case class And(left: Expression, right: Expression)
extends BinaryOperator with
}
}
+ override def semanticEquals(other: Expression): Boolean = this.getClass
== other.getClass && {
+ // Non-deterministic expressions cannot be semantic equal
+ if (!deterministic || !other.deterministic) return false
+
+ // We already know both expressions are And, so we can tolerate
ordering different
+ // Recursively call semanticEquals on subexpressions to check the
equivalency of two seqs.
+ var elements1 = splitConjunctivePredicates(this)
+ val elements2 = splitConjunctivePredicates(other)
+ // We can recursively call semanticEquals to check the equivalency for
subexpressions, but
+ // there is no simple solution to compare the equivalency of sequence
of expressions.
+ // Expression class doesn't have order, so we couldn't sort them. We
can neither use
+ // set comparison as Set doesn't support custom compare function,
which is semanticEquals.
+ // To check the equivalency of elements1 and elements2, we first
compare their size. Then
+ // for each element in elements2, we remove its first semantically
equivalent expression from
+ // elements1. If they are semantically equivalent, elements1 should be
empty at the end.
+ elements1.size == elements2.size && {
+ for (e <- elements2) elements1 =
removeFirstSemanticEquivalent(elements1, e)
+ elements1.isEmpty
--- End diff --
Consider this example
`e1 = And(a, And(b, c))`
`e2 = And(And(a,b), c))`
They are semantically equivalent, but will return false in your code.
`splitConjunctivePredicates` will crunch the expression tree in to a
sequence of (a, b, c).
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
