[jira] [Commented] (SPARK-36918) unionByName shouldn't consider types when comparing structs

["Apache Spark (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-36918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17423745#comment-17423745 ] 

Apache Spark commented on SPARK-36918:
--------------------------------------

User 'Kimahriman' has created a pull request for this issue:
https://github.com/apache/spark/pull/34166

> unionByName shouldn't consider types when comparing structs
> -----------------------------------------------------------
>
>                 Key: SPARK-36918
>                 URL: https://issues.apache.org/jira/browse/SPARK-36918
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.2.0
>            Reporter: Adam Binford
>            Priority: Major
>
> Improvement/follow-on of https://issues.apache.org/jira/browse/SPARK-35290.
> We use StructType.sameType to see if we need to recreate the struct, but this can lead to false positives if the structure is the same but the types are different, and will lead to simply creating a new struct that's exactly the same as the original. This can cause significant overhead when unioning multiple deeply nested nullable structs, as each time it's recreated it gets wrapped in a If(IsNull()). Only comparing the field names can lead to more efficient plans.



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