Github user ankurdave commented on a diff in the pull request:
https://github.com/apache/spark/pull/9089#discussion_r41836429
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -362,14 +362,35 @@ class Analyzer(
j
case Some((oldRelation, newRelation)) =>
val attributeRewrites =
AttributeMap(oldRelation.output.zip(newRelation.output))
- val newRight = right transformUp {
- case r if r == oldRelation => newRelation
- } transformUp {
- case other => other transformExpressions {
- case a: Attribute => attributeRewrites.get(a).getOrElse(a)
+ def applyRewrites(plan: LogicalPlan): LogicalPlan =
+ plan transformUp {
+ case r if r == oldRelation => newRelation
+ } transformUp {
+ case other => other transformExpressions {
+ case a: Attribute =>
attributeRewrites.get(a).getOrElse(a)
+ }
}
- }
- j.copy(right = newRight)
+ val newRight = applyRewrites(right)
+ // Also apply the rewrites to foreign keys on the left side,
because these are meant to
+ // reference the right side.
+ val newLeft =
+ if (left.keys.nonEmpty) {
+ left.transform {
+ case KeyHint(keys, child) =>
+ val newKeys = keys.collect {
+ case ForeignKey(attr, referencedRelation,
referencedAttr) =>
+ ForeignKey(
+ attr,
+ applyRewrites(referencedRelation),
+
attributeRewrites.get(referencedAttr).getOrElse(referencedAttr))
+ case other => other
+ }
+ KeyHint((keys ++ newKeys).distinct, child)
--- End diff --
Good eye! This is to accommodate future self-joins. If we got rid of the
old foreign keys, a future self-join would not recognize that the new keys
applied to it, because the attributes would have been rewritten. I just added
a comment noting this.
There's [a unit
test](https://github.com/apache/spark/pull/9089/files#diff-09ca3beb9c48d89b5fcf248e48d888ddR261)
that covers this (fails if you remove the old keys).
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