[SPARK-8218][SQL] Binary log math function update.

[rxin]

Some minor updates based on after merging #6725.

[rxin]

cc @davies for review.

[SparkQA]

Test build #35097 has finished for PR 6871 at commit a7c1522.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class ElementwiseProduct(VectorTransformer):
  • class MatrixUDT(UserDefinedType):
  • case class UnaryPositive(child: Expression) extends UnaryArithmetic
  • case class Logarithm(left: Expression, right: Expression)
  • case class SetCommand(kv: Option[(String, Option[String])]) extends RunnableCommand with Logging
  • // Add jar to isolated hive (metadataHive) class loader.

[SparkQA]

Test build #35155 has finished for PR 6871 at commit ab51542.

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

[rxin]

Jenkins, retest this please.

[SparkQA]

Test build #35175 has finished for PR 6871 at commit ab51542.

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

[yjshen]

I prefer to remove this single parameter constructor, because this would make both ln and log(c) express the same thing in a SQL expression.

And also complex the binary log here to check its first argument branch in both eval & genCode

[rxin]

I think that's a good idea. Can you fix it in your pr? I'm gonig to merge this one first.

[yjshen]

Yes, already fix this in my pr. :)

[rxin]

I like that idea.