[jira] [Created] (SPARK-27582) Add Dataset DSL for left_anti and left_semi joins

["Stanislav Bytsko (JIRA)" <ji...@apache.org>]

Stanislav Bytsko created SPARK-27582:
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             Summary: Add Dataset DSL for left_anti and left_semi joins
                 Key: SPARK-27582
                 URL: https://issues.apache.org/jira/browse/SPARK-27582
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 2.4.2
            Reporter: Stanislav Bytsko


Currently we have
{code:java}
org.apache.spark.sql.Dataset[T]#joinWith[U](other: Dataset[U], condition: Column, joinType: String): Dataset[(T, U)]
{code}
which explicitly excludes left_anti and left_semi joins, which is understandable, because result would have different signature.
I think it's easily fixed drawback, which accepts 2 solutions I can think of:
- Extend current joinWith to return null for second (_2) item in the tuple. Not ideal as no-one likes nulls, but workable, as client should be able to handle that by doing {code}.map(_._1){code} immediately afterwards
- Add 2 new methods {code}org.apache.spark.sql.Dataset[T]#joinSemiWith[U](other: Dataset[U], condition: Column): Dataset[T]{code} and {code}org.apache.spark.sql.Dataset[T]#joinAntiWith[U](other: Dataset[U], condition: Column): Dataset[T]{code} which is much nicer, but adds 2 methods to the API.






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