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Posted to issues@spark.apache.org by "Wenchen Fan (Jira)" <ji...@apache.org> on 2020/10/06 08:35:00 UTC
[jira] [Resolved] (SPARK-33035) Updates the obsoleted entries of
attribute mapping in QueryPlan#transformUpWithNewOutput
[ https://issues.apache.org/jira/browse/SPARK-33035?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Wenchen Fan resolved SPARK-33035.
---------------------------------
Fix Version/s: 3.1.0
Resolution: Fixed
Issue resolved by pull request 29911
[https://github.com/apache/spark/pull/29911]
> Updates the obsoleted entries of attribute mapping in QueryPlan#transformUpWithNewOutput
> ----------------------------------------------------------------------------------------
>
> Key: SPARK-33035
> URL: https://issues.apache.org/jira/browse/SPARK-33035
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 3.0.1, 3.1.0
> Reporter: Takeshi Yamamuro
> Assignee: Takeshi Yamamuro
> Priority: Major
> Fix For: 3.1.0
>
>
> This ticket aims at fixing corner-case bugs in the `QueryPlan#transformUpWithNewOutput` that is used to propagate updated `ExprId`s in a bottom-up way. Let's say we have a rule to simply assign new `ExprId`s in a projection list like this;
> {code}
> case class TestRule extends Rule[LogicalPlan] {
> override def apply(plan: LogicalPlan): LogicalPlan = plan.transformUpWithNewOutput {
> case p @ Project(projList, _) =>
> val newPlan = p.copy(projectList = projList.map { _.transform {
> // Assigns a new `ExprId` for references
> case a: AttributeReference => Alias(a, a.name)()
> }}.asInstanceOf[Seq[NamedExpression]])
> val attrMapping = p.output.zip(newPlan.output)
> newPlan -> attrMapping
> }
> }
> {code}
> Then, this rule is applied into a plan below;
> {code}
> (3) Project [a#5, b#6]
> +- (2) Project [a#5, b#6]
> +- (1) Project [a#5, b#6]
> +- LocalRelation <empty>, [a#5, b#6]
> {code}
> In the first transformation, the rule assigns new `ExprId`s in `(1) Project` (e.g., a#5 AS a#7, b#6 AS b#8). In the second transformation, the rule corrects the input references of `(2) Project` first by using attribute mapping given from `(1) Project` (a#5->a#7 and b#6->b#8) and then assigns new `ExprId`s (e.g., a#7 AS a#9, b#8 AS b#10). But, in the third transformation, the rule fails because it tries to correct the references of `(3) Project` by using incorrect attribute mapping (a#7->a#9 and b#8->b#10) even though the correct one is a#5->a#9 and b#6->b#10.
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