Github user sameeragarwal commented on a diff in the pull request:
https://github.com/apache/spark/pull/15319#discussion_r84646767
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/QueryPlan.scala
---
@@ -74,20 +74,98 @@ abstract class QueryPlan[PlanType <:
QueryPlan[PlanType]] extends TreeNode[PlanT
* additional constraint of the form `b = 5`
*/
private def inferAdditionalConstraints(constraints: Set[Expression]):
Set[Expression] = {
+ // Collect alias from expressions to avoid producing non-converging
set of constraints
+ // for recursive functions.
+ //
+ // Don't apply transform on constraints if the replacement will cause
an recursive deduction,
+ // when that happens a non-converging set of constraints will be
created and finally throw
+ // OOM Exception.
+ // For more details, refer to
https://issues.apache.org/jira/browse/SPARK-17733
+ val aliasMap = AttributeMap((expressions ++
children.flatMap(_.expressions)).collect {
+ case a: Alias => (a.toAttribute, a.child)
+ })
+
+ val equalExprSets = generateEqualExpressionSets(constraints, aliasMap)
+
var inferredConstraints = Set.empty[Expression]
constraints.foreach {
case eq @ EqualTo(l: Attribute, r: Attribute) =>
- inferredConstraints ++= (constraints - eq).map(_ transform {
- case a: Attribute if a.semanticEquals(l) => r
+ val candidateConstraints = constraints - eq
+ inferredConstraints ++= candidateConstraints.map(_ transform {
+ case a: Attribute if a.semanticEquals(l) &&
+ !isRecursiveDeduction(r, aliasMap, equalExprSets) => r
})
- inferredConstraints ++= (constraints - eq).map(_ transform {
- case a: Attribute if a.semanticEquals(r) => l
+ inferredConstraints ++= candidateConstraints.map(_ transform {
+ case a: Attribute if a.semanticEquals(r) &&
+ !isRecursiveDeduction(l, aliasMap, equalExprSets) => l
})
case _ => // No inference
}
inferredConstraints -- constraints
}
+ /*
+ * Generate a sequence of expression sets from constraints, where each
set stores an equivalence
+ * class of expressions. For example, Set(`a = b`, `b = c`, `e = f`)
will generate the following
+ * expression sets: (Set(a, b, c), Set(e, f)). This will be used to
search all expressions equal
+ * to an selected attribute.
+ */
+ private def generateEqualExpressionSets(
+ constraints: Set[Expression],
+ aliasMap: AttributeMap[Expression]): Seq[Set[Expression]] = {
+ var equalExprSets = Seq.empty[Set[Expression]]
+ constraints.foreach {
+ case eq @ EqualTo(l: Attribute, r: Attribute) =>
+ // Transform [[Alias]] to its child.
+ val left = aliasMap.getOrElse(l, l)
+ val right = aliasMap.getOrElse(r, r)
+ // Get the expression set for equivalence class of expressions.
+ val leftEqualSet = getEqualExprSet(left,
equalExprSets).getOrElse(Set.empty[Expression])
+ val rightEqualSet = getEqualExprSet(right,
equalExprSets).getOrElse(Set.empty[Expression])
+ if (!leftEqualSet.isEmpty && !rightEqualSet.isEmpty) {
--- End diff --
nit: can use `leftEqualSet.nonEmpty` and `rightEqualSet.nonEmpty` here and
at other places
---
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]
