You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@spark.apache.org by "L. C. Hsieh (Jira)" <ji...@apache.org> on 2021/05/21 17:53:00 UTC
[jira] [Resolved] (SPARK-35439) Children subexpr should come first
than parent subexpr in subexpression elimination
[ https://issues.apache.org/jira/browse/SPARK-35439?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
L. C. Hsieh resolved SPARK-35439.
---------------------------------
Fix Version/s: 3.2.0
Assignee: L. C. Hsieh (was: Apache Spark)
Resolution: Fixed
The issue is resolved at https://github.com/apache/spark/pull/32586
> 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: Sub-task
> Components: SQL
> Affects Versions: 3.2.0
> Reporter: L. C. Hsieh
> Assignee: L. C. Hsieh
> Priority: Major
> Fix For: 3.2.0
>
>
> 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.
> For example, we have two different expressions Add(Literal(1), Literal(2)) and Add(Literal(3), add).
> Case 1: child subexpr comes first. Replacing HashMap with LinkedHashMap can deal with it.
> addExprTree(add)
> addExprTree(Add(Literal(3), add))
> addExprTree(Add(Literal(3), add))
> Case 2: parent subexpr comes first. For this case, we need to sort equivalent expressions.
> addExprTree(Add(Literal(3), add)) => We add `Add(Literal(3), add)` into the map first, then add `add` into the map
> addExprTree(add)
> addExprTree(Add(Literal(3), add))
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org