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https://issues.apache.org/jira/browse/SPARK-30957?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hyukjin Kwon resolved SPARK-30957.
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Resolution: Won't Fix
> Null-safe variant of Dataset.join(Dataset[_], Seq[String])
> ----------------------------------------------------------
>
> Key: SPARK-30957
> URL: https://issues.apache.org/jira/browse/SPARK-30957
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.1.0
> Reporter: Enrico Minack
> Priority: Major
>
> The {{Dataset.join(Dataset, Seq[String])}} method provides extra convenience
> over {{Dataset.join(Dataset, joinExprs: Column)}} as it does not duplicate
> the join columns {{Seq[String]}} in the result {{DataFrame}}. Those columns
> are compared with {{===}}. When those join columns need to be compared
> null-safe with {{<=>}}, the join condition becomes very verbose and requires
> extra {{drop}} operations:
> {code:java}
> df1.join(df2, df1("a") <=> df2("a") && df1("b") <=>
> df2("b")).drop(df2("a")).drop(df2("b")).show()
> {code}
> Elegant would be the following null-safe join operation:
> {code:java}
> df1.joinNullSafe(df2, joinColumns)
> {code}
> Possible namings:
> - {{Dataset.joinNullSafe(Dataset[_], Seq[String])}}
> - {{Dataset.joinWithNulls(Dataset[_], Seq[String])}}
> - {{Dataset.join(Dataset[_], Seq[String], <=>)}}
> *I am happy to provide a PR if this Dataset API extension is appreciated.*
> This request has been sent to the Apache Spark user and
> [dev|http://apache-spark-developers-list.1001551.n3.nabble.com/Fwd-dataframe-null-safe-joins-given-a-list-of-columns-tt28842.html]
> mailing list by Marcelo Valle.
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