cloud-fan commented on a change in pull request #25204:
[SPARK-28441][SQL][Python] Fix error when PythonUDF is used in correlated
scalar subquery
URL: https://github.com/apache/spark/pull/25204#discussion_r305670236
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/subquery.scala
##########
@@ -318,17 +318,30 @@ object RewriteCorrelatedScalarSubquery extends
Rule[LogicalPlan] {
/**
* Statically evaluate an expression containing zero or more placeholders,
given a set
- * of bindings for placeholder values.
+ * of bindings for placeholder values, if the expression is evaluable. If it
is not,
+ * bind statically evaluated expression results to an expression.
*/
- private def evalExpr(expr: Expression, bindings: Map[ExprId, Option[Any]]) :
Option[Any] = {
+ private def bindingExpr(
+ expr: Expression,
+ bindings: Map[ExprId, Option[Expression]]): Option[Expression] = {
val rewrittenExpr = expr transform {
case r: AttributeReference =>
bindings(r.exprId) match {
- case Some(v) => Literal.create(v, r.dataType)
+ case Some(v) => v
case None => Literal.default(NullType)
}
}
- Option(rewrittenExpr.eval())
+ if (rewrittenExpr.find(_.isInstanceOf[PythonUDF]).isDefined) {
+ // SPARK-28441: `PythonUDF` can't be statically evaluated.
Review comment:
We can't call `Expression.eval(null)` if it's not foldable, otherwise
exception may be thrown:
1. `AttributeReference.eval(null)` fails with NPE
2. `Nondeterministic.eval(null)` fails because it needs to be initialized
first
Whatever hack we use, I'd expect it makes the expression foldable.
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