[GitHub] [spark] HyukjinKwon commented on a change in pull request #26286: [SPARK-26739][SQL] Standardized Join Types for DataFrames

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HyukjinKwon commented on a change in pull request #26286: [SPARK-26739][SQL] Standardized Join Types for DataFrames
URL: https://github.com/apache/spark/pull/26286#discussion_r339977592
 
 

 ##########
 File path: sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
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 @@ -980,21 +980,48 @@ class Dataset[T] private[sql](
    * `DataFrame`s, you will NOT be able to reference any columns after the join, since
    * there is no way to disambiguate which side of the join you would like to reference.
    *
+   * @deprecated Use
+   * [[Dataset.join(Dataset[_], Seq[String], JoinType): DataFrame* this version]] instead
+   *
    * @group untypedrel
    * @since 2.0.0
    */
+  @deprecated("Use [[Dataset#join(Dataset[_], Seq[String], JoinType): DataFrame* this]]", "3.0.0")
   def join(right: Dataset[_], usingColumns: Seq[String], joinType: String): DataFrame = {
+    join(right, usingColumns, JoinType(joinType))
+  }
+
+  /**
+   * Equi-join with another `DataFrame` using the given columns. A cross join with a predicate
+   * is specified as an inner join. If you would explicitly like to perform a cross join use the
+   * `crossJoin` method.
+   *
+   * Different from other join functions, the join columns will only appear once in the output,
+   * i.e. similar to SQL's `JOIN USING` syntax.
+   *
+   * @param right Right side of the join operation.
+   * @param usingColumns Names of the columns to join on. This columns must exist on both sides.
+   * @param joinType Type of join to perform (instance of [[JoinType!]]. Default [[Inner]].
+   *
+   * @note If you perform a self-join using this function without aliasing the input
+   * `DataFrame`s, you will NOT be able to reference any columns after the join, since
+   * there is no way to disambiguate which side of the join you would like to reference.
+   *
+   * @group untypedrel
+   * @since 2.0.0
+   */
+  def join(right: Dataset[_], usingColumns: Seq[String], joinType: JoinType): DataFrame = {
 
 Review comment:
   `JoinType` isn't supposed to be an API. It's internal purpose and under catalyst. Why don't we just add enums?

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