[
https://issues.apache.org/jira/browse/SPARK-35439?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
L. C. Hsieh updated SPARK-35439:
--------------------------------
Summary: Children subexpr should come first than parent subexpr in
subexpression elimination (was: Use LinkedHashMap as the map of equivalent
expressions to preserve insertion order)
> Children subexpr should come first than parent subexpr in subexpression
> elimination
> -----------------------------------------------------------------------------------
>
> Key: SPARK-35439
> URL: https://issues.apache.org/jira/browse/SPARK-35439
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.0.2, 3.1.1, 3.2.0
> Reporter: L. C. Hsieh
> Assignee: Apache Spark
> Priority: Minor
>
> EquivalentExpressions maintains a map of equivalent expressions. It is
> HashMap now so the insertion order is not guaranteed to be preserved later.
> Subexpression elimination relies on retrieving subexpressions from the map.
> If there is child-parent relationships among the subexpressions, we want the
> child expressions come first than parent expressions, so we can replace child
> expressions in parent expressions with subexpression evaluation.
> Although we add expressions recursively into the map with depth-first
> approach, when we retrieve the map values, it is not guaranteed that the
> order is preserved. We should use LinkedHashMap for this usage.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
