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https://issues.apache.org/jira/browse/SPARK-35739?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Brandon Dahler updated SPARK-35739:
-----------------------------------
    Description: 
h2. Problem

When using Spark SQL with Java, the required syntax to utilize the following 
two overloads are unnatural and not obvious to developers that haven't had to 
interoperate with Scala before:
{code:java}
def join(right: Dataset[_], usingColumns: Seq[String]): DataFrame
def join(right: Dataset[_], usingColumns: Seq[String], joinType: String): 
DataFrame
{code}
Examples:

Java 11 
{code:java}
Dataset<Row> dataset1 = ...;
Dataset<Row> dataset2 = ...;

// Overload with multiple usingColumns, no join type
dataset1
  .join(dataset2, JavaConverters.asScalaBuffer(List.of("column", "column2))
  .show();

// Overload with multiple usingColumns and a join type
dataset1
  .join(
    dataset2,
    JavaConverters.asScalaBuffer(List.of("column", "column2")),
    "left")
  .show();
{code}
 
 Additionally there is no overload that takes a single usingColumnn and a 
joinType, forcing the developer to use the Seq[String] overload regardless of 
language.

Examples:

Scala
{code:java}
val dataset1 :DataFrame = ...;
val dataset2 :DataFrame = ...;

dataset1
  .join(dataset2, Seq("column"), "left")
  .show();
{code}
 
 Java 11
{code:java}
Dataset<Row> dataset1 = ...;
Dataset<Row> dataset2 = ...;

dataset1
 .join(dataset2, JavaConverters.asScalaBuffer(List.of("column")), "left")
 .show();
{code}
h2. Proposed Improvement

Add 3 additional overloads to Dataset:
  
{code:java}
def join(right: Dataset[_], usingColumn: List[String]): DataFrame
def join(right: Dataset[_], usingColumn: String, joinType: String): DataFrame
def join(right: Dataset[_], usingColumn: List[String], joinType: String): 
DataFrame
{code}

  was:
h2. Problem
When using Spark SQL with Java, the required syntax to utilize the following 
two overloads are unnatural and not obvious to developers that haven't had to 
interoperate with Scala before:
{code:java}
def join(right: Dataset[_], usingColumns: Seq[String]): DataFrame
def join(right: Dataset[_], usingColumns: Seq[String], joinType: String): 
DataFrame
{code}
Examples:

Java 11 
{code:java}
Dataset<Row> dataset1 = ...;
Dataset<Row> dataset2 = ...;

// Overload with multiple usingColumns, no join type
dataset1
  .join(dataset2, JavaConverters.asScalaBuffer(List.of("column", "column2))
  .show();

// Overload with multiple usingColumns and a join type
dataset1
  .join(
    dataset2,
    JavaConverters.asScalaBuffer(List.of("column", "column2")),
    "left")
  .show();
{code}
 
Additionally there is no overload that takes a single usingColumnn and a 
joinType, forcing the developer to use the Seq[String] overload regardless of 
language.

Examples:

Scala
{code:java}
val dataset1 :DataFrame = ...;
val dataset2 :DataFrame = ...;

dataset1
  .join(dataset2, Seq("column"))
  .show();
{code}
 
Java 11
{code:java}
Dataset<Row> dataset1 = ...;
Dataset<Row> dataset2 = ...;

dataset1
 .join(dataset2, JavaConverters.asScalaBuffer(List.of("column")))
 .show();
{code}

h2. Proposed Improvement

Add 3 additional overloads to Dataset:
 
{code:java}
def join(right: Dataset[_], usingColumn: List[String]): DataFrame
def join(right: Dataset[_], usingColumn: String, joinType: String): DataFrame
def join(right: Dataset[_], usingColumn: List[String], joinType: String): 
DataFrame
{code}


> [Spark Sql] Add Java-comptable Dataset.join overloads
> -----------------------------------------------------
>
>                 Key: SPARK-35739
>                 URL: https://issues.apache.org/jira/browse/SPARK-35739
>             Project: Spark
>          Issue Type: Improvement
>          Components: Java API, SQL
>    Affects Versions: 2.0.0, 3.0.0
>            Reporter: Brandon Dahler
>            Priority: Minor
>
> h2. Problem
> When using Spark SQL with Java, the required syntax to utilize the following 
> two overloads are unnatural and not obvious to developers that haven't had to 
> interoperate with Scala before:
> {code:java}
> def join(right: Dataset[_], usingColumns: Seq[String]): DataFrame
> def join(right: Dataset[_], usingColumns: Seq[String], joinType: String): 
> DataFrame
> {code}
> Examples:
> Java 11 
> {code:java}
> Dataset<Row> dataset1 = ...;
> Dataset<Row> dataset2 = ...;
> // Overload with multiple usingColumns, no join type
> dataset1
>   .join(dataset2, JavaConverters.asScalaBuffer(List.of("column", "column2))
>   .show();
> // Overload with multiple usingColumns and a join type
> dataset1
>   .join(
>     dataset2,
>     JavaConverters.asScalaBuffer(List.of("column", "column2")),
>     "left")
>   .show();
> {code}
>  
>  Additionally there is no overload that takes a single usingColumnn and a 
> joinType, forcing the developer to use the Seq[String] overload regardless of 
> language.
> Examples:
> Scala
> {code:java}
> val dataset1 :DataFrame = ...;
> val dataset2 :DataFrame = ...;
> dataset1
>   .join(dataset2, Seq("column"), "left")
>   .show();
> {code}
>  
>  Java 11
> {code:java}
> Dataset<Row> dataset1 = ...;
> Dataset<Row> dataset2 = ...;
> dataset1
>  .join(dataset2, JavaConverters.asScalaBuffer(List.of("column")), "left")
>  .show();
> {code}
> h2. Proposed Improvement
> Add 3 additional overloads to Dataset:
>   
> {code:java}
> def join(right: Dataset[_], usingColumn: List[String]): DataFrame
> def join(right: Dataset[_], usingColumn: String, joinType: String): DataFrame
> def join(right: Dataset[_], usingColumn: List[String], joinType: String): 
> DataFrame
> {code}



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