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https://issues.apache.org/jira/browse/SPARK-60135?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-60135:
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Labels: pull-request-available (was: )
> Prune unnecessary subquery-expression traversal in DeduplicateRelations
> -----------------------------------------------------------------------
>
> Key: SPARK-60135
> URL: https://issues.apache.org/jira/browse/SPARK-60135
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 4.1.1, 5.0.0
> Reporter: Hussein Awala
> Priority: Major
> Labels: pull-request-available
>
> DeduplicateRelations.deduplicate unconditionally calls
> plan.transformExpressions with a partial function that matches only
> SubqueryExpression. This also walks operator expressions that cannot contain
> a subquery.
> QueryPlan propagates expression tree-pattern bits, and SubqueryExpression
> inherits the PLAN_EXPRESSION marker. A narrowly scoped optimization can skip
> this expression scan when that marker is absent from the plan, and prune
> expression subtrees without the marker when the scan is needed.
> The relation-renewal traversal, attribute remapping, subquery recursion and
> processing order must remain unchanged. The expression transform must retain
> UnknownRuleId because its closure reads and updates traversal state;
> ineffective-rule memoization would be inappropriate here.
> Suggested validation uses generic Catalyst plans: projects containing
> arithmetic/literal expressions, subqueries wrapped in aliases or other
> expressions, nested/correlated subqueries, and the same subquery object
> reused in multiple positions.
> This is narrower than SPARK-49881 (conditional rule-wide skipping), and
> distinct from SPARK-59452 (wide UNION branch comparisons and related
> synthetic self-join overhead).
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