Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1981#discussion_r64778861
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/logical/operators.scala
---
@@ -298,11 +338,40 @@ case class Join(
val resolvedJoin = super.validate(tableEnv).asInstanceOf[Join]
if (!resolvedJoin.condition.forall(_.resultType == BOOLEAN_TYPE_INFO))
{
failValidation(s"filter expression ${resolvedJoin.condition} is not
a boolean")
- } else if (!ambiguousName.isEmpty) {
+ } else if (ambiguousName.nonEmpty) {
failValidation(s"join relations with ambiguous names:
${ambiguousName.mkString(", ")}")
}
+
+ resolvedJoin.condition.foreach(testJoinCondition(_))
resolvedJoin
}
+
+ private def testJoinCondition(expression: Expression): Unit = {
+ def checkIfJoinCondition(exp : BinaryComparison) = exp.children match {
+ case (x : JoinFieldReference) :: (y : JoinFieldReference) :: Nil
+ if x.isFromLeftInput != y.isFromLeftInput => Unit
+ case _ => failValidation(
+ s"Only join predicates supported. For non-join predicates use
Table#where.")
+ }
+
+ var equiJoinFound = false
+ def validateConditions(exp: Expression, isAndBranch: Boolean): Unit =
exp match {
+ case x: And => x.children.foreach(validateConditions(_, isAndBranch))
+ case x: Or => x.children.foreach(validateConditions(_, isAndBranch =
false))
+ case x: EqualTo =>
+ if (isAndBranch) {
+ equiJoinFound = true
+ }
+ checkIfJoinCondition(x)
+ case x: BinaryComparison => checkIfJoinCondition(x)
+ case x => failValidation(s"Unsupported condition type:
${x.getClass.getSimpleName}.")
+ }
+
+ validateConditions(expression, isAndBranch = true)
+ if (!equiJoinFound) {
+ failValidation(s"At least one equi-join required.")
--- End diff --
Add the whole join predicate to the error message?
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