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https://issues.apache.org/jira/browse/SPARK-59501?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-59501:
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Labels: pull-request-available (was: )
> Unnecessary allocations in unchanged TreeNode traversals
> --------------------------------------------------------
>
> Key: SPARK-59501
> URL: https://issues.apache.org/jira/browse/SPARK-59501
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 4.2.0
> Reporter: Ben Hollis
> Priority: Minor
> Labels: pull-request-available
>
> Catalyst rules repeatedly traverse large, immutable plan and expression trees
> that they mostly leave unchanged. Even when a node and its subtree are not
> modified, the generic TreeNode traversal still allocates on every node.
> This cost is paid by every applicable analyzer and optimizer rule, on every
> pass, and scales with tree size, so queries whose analyzed plan expands into
> hundreds of branches amplify it. On a synthetic 500-branch compatibility view
> (4,001 analyzed plan nodes, ~378K expression occurrences), the unchanged-tree
> allocation overhead dominates optimizer time.
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