[SPARK-16853][SQL] fixes encoder error in DataSet typed select

[clockfly]

What changes were proposed in this pull request?

For DataSet typed select:

def select[U1: Encoder](c1: TypedColumn[T, U1]): Dataset[U1]

If type T is a case class or a tuple class that is not atomic, the resulting logical plan's schema will mismatch with Dataset[T] encoder's schema, which will cause encoder error and throw AnalysisException.

Before change:

scala> case class A(a: Int, b: Int)
scala> Seq((0, A(1,2))).toDS.select($"_2".as[A])
org.apache.spark.sql.AnalysisException: cannot resolve '`a`' given input columns: [_2];
..

After change:

scala> case class A(a: Int, b: Int)
scala> Seq((0, A(1,2))).toDS.select($"_2".as[A]).show
+---+---+
|  a|  b|
+---+---+
|  1|  2|
+---+---+

How was this patch tested?

Unit test.

[SparkQA]

Test build #63151 has finished for PR 14474 at commit 2b2c1d6.

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

[SparkQA]

Test build #63199 has finished for PR 14474 at commit 952ec92.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[cloud-fan]

LGTM, though the test hasn't passed.

[SparkQA]

Test build #63204 has finished for PR 14474 at commit d9b5a40.

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

[cloud-fan]

how about typed select that returns case class or tuple?

[clockfly]

@cloud-fan

This follows existing test case name, for example, for select 2, current name is

test("select 2, primitive and tuple") {

https://github.com/apache/spark/pull/14474/files#diff-3836bd1fc5ae9c8b8ac4bdb2b9944159L196

[SparkQA]

Test build #63206 has finished for PR 14474 at commit 3d90a68.

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

[cloud-fan]

thanks, merging to master!

[rxin]

Is this a bug fix? If yes, shouldn't we merge it in 2.0?

[cloud-fan]

it's a bug since the very beginning, should we merge it to 1.6 too?

[zsxwing]

Should this one be merged into branch-2.0?

[cloud-fan]

@clockfly can you create a new PR against 2.0? thanks!