[SPARK-7990][SQL] Add methods to facilitate equi-join on multiple joining keys

[viirya]

JIRA: https://issues.apache.org/jira/browse/SPARK-7990

[SparkQA]

Test build #34097 has finished for PR 6616 at commit cc90015.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • trait TypeCheckResult
  • case class TypeCheckFailure(message: String) extends TypeCheckResult
  • abstract class UnaryArithmetic extends UnaryExpression
  • case class UnaryMinus(child: Expression) extends UnaryArithmetic
  • case class Sqrt(child: Expression) extends UnaryArithmetic
  • case class Abs(child: Expression) extends UnaryArithmetic
  • case class BitwiseNot(child: Expression) extends UnaryArithmetic
  • case class MaxOf(left: Expression, right: Expression) extends BinaryArithmetic
  • case class MinOf(left: Expression, right: Expression) extends BinaryArithmetic
  • case class Atan2(left: Expression, right: Expression)
  • case class Hypot(left: Expression, right: Expression)
  • case class EqualTo(left: Expression, right: Expression) extends BinaryComparison

[SparkQA]

Test build #34099 has finished for PR 6616 at commit 0400e89.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[rxin]

let's change the argument name in python as explained in the jira ticket

[viirya]

ok.

[SparkQA]

Test build #34185 has finished for PR 6616 at commit c43722c.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[viirya]

retest this please.

[SparkQA]

Test build #34189 has finished for PR 6616 at commit c43722c.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #34235 has finished for PR 6616 at commit cd5c888.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[viirya]

@rxin Any more comments?

[rxin]

Thanks. I'm merging this.