cloud-fan commented on code in PR #49351:
URL: https://github.com/apache/spark/pull/49351#discussion_r1903881211
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala:
##########
@@ -539,48 +582,58 @@ case class Union(
children.length > 1 && !(byName || allowMissingCol) && childrenResolved &&
allChildrenCompatible
}
- private lazy val lazyOutput: Seq[Attribute] = computeOutput()
-
- private def computeOutput(): Seq[Attribute] =
Union.mergeChildOutputs(children.map(_.output))
-
- /**
- * Maps the constraints containing a given (original) sequence of attributes
to those with a
- * given (reference) sequence of attributes. Given the nature of union, we
expect that the
- * mapping between the original and reference sequences are symmetric.
- */
- private def rewriteConstraints(
- reference: Seq[Attribute],
- original: Seq[Attribute],
- constraints: ExpressionSet): ExpressionSet = {
- require(reference.size == original.size)
- val attributeRewrites = AttributeMap(original.zip(reference))
- constraints.map(_ transform {
- case a: Attribute => attributeRewrites(a)
- })
- }
+ override protected def withNewChildrenInternal(newChildren:
IndexedSeq[LogicalPlan]): Union =
+ copy(children = newChildren)
+}
- private def merge(a: ExpressionSet, b: ExpressionSet): ExpressionSet = {
- val common = a.intersect(b)
- // The constraint with only one reference could be easily inferred as
predicate
- // Grouping the constraints by it's references so we can combine the
constraints with same
- // reference together
- val othera = a.diff(common).filter(_.references.size ==
1).groupBy(_.references.head)
- val otherb = b.diff(common).filter(_.references.size ==
1).groupBy(_.references.head)
- // loose the constraints by: A1 && B1 || A2 && B2 -> (A1 || A2) && (B1
|| B2)
- val others = (othera.keySet intersect otherb.keySet).map { attr =>
- Or(othera(attr).reduceLeft(And), otherb(attr).reduceLeft(And))
- }
- common ++ others
- }
+/**
+ * The logical node for recursion, that contains a initial (anchor) and a
recursion describing term,
+ * that contains an [[UnionLoopRef]] node.
+ * The node is very similar to [[Union]] because the initial and "generated"
children are union-ed
+ * and it is also similar to a loop because the recursion continues until the
last generated child
+ * is not empty.
+ *
+ * @param id The id of the loop, inherited from [[CTERelationDef]]
+ * @param anchor The plan of the initial element of the loop.
+ * @param recursion The plan that describes the recursion with an
[[UnionLoopRef]] node.
+ * @param limit An optional limit that can be pushed down to the node to stop
the loop earlier.
+ */
+case class UnionLoop(
+ id: Long,
+ anchor: LogicalPlan,
+ recursion: LogicalPlan,
+ limit: Option[Int] = None) extends UnionBase {
+ override def children: Seq[LogicalPlan] = Seq(anchor, recursion)
+
+ override protected def withNewChildrenInternal(newChildren:
IndexedSeq[LogicalPlan]): UnionLoop =
+ copy(anchor = newChildren(0), recursion = newChildren(1))
+}
- override protected lazy val validConstraints: ExpressionSet = {
- children
- .map(child => rewriteConstraints(children.head.output, child.output,
child.constraints))
- .reduce(merge(_, _))
+/**
+ * The recursive reference in the recursive term of an [[UnionLoop]] node.
+ *
+ * @param loopId The id of the loop, inherited from [[CTERelationRef]]
+ * @param output The output attributes of this recursive reference.
+ * @param accumulated If false the the reference stands for the result of the
previous iteration.
+ * If it is true then then it stands for the union of all
previous iteration
+ * results.
+ */
+case class UnionLoopRef(
Review Comment:
where do we create `UnionLoopRef`?
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