[SPARK-8826] [SQL] Fix ClassCastException in GeneratedAggregate

[navis]

When codegen is disabled, ClassCastException is thrown in some cases.

[SparkQA]

Test build #36543 has finished for PR 7225 at commit 9badf54.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class InterpretedProjection(expressions: Seq[Expression], mutableRow: Boolean = false)
  • case class Hex(child: Expression) extends UnaryExpression with ExpectsInputTypes
  • case class UnHex(child: Expression) extends UnaryExpression with ExpectsInputTypes
  • case class ShiftLeft(left: Expression, right: Expression)
  • case class ShiftRight(left: Expression, right: Expression)
  • case class ShiftRightUnsigned(left: Expression, right: Expression)
  • case class Levenshtein(left: Expression, right: Expression) extends BinaryExpression

[cloud-fan]

Why this change? If you want to use mutable row in projection, you can use InterpretedMutableProjection.

[navis]

Yes, but InterpretedProjection and InterpretedMutableProjection has different semantic on returning object. It would be same thing if call setTarget() before each apply() call but I wanted keep it simple without incurring another problem.

[SparkQA]

Test build #36545 has finished for PR 7225 at commit 5f6a18c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class InterpretedProjection(expressions: Seq[Expression], mutableRow: Boolean = false)
  • case class Hex(child: Expression) extends UnaryExpression with ExpectsInputTypes
  • case class UnHex(child: Expression) extends UnaryExpression with ExpectsInputTypes
  • case class ShiftLeft(left: Expression, right: Expression)
  • case class ShiftRight(left: Expression, right: Expression)
  • case class ShiftRightUnsigned(left: Expression, right: Expression)

[JoshRosen]

Doesn't the use of GeneratedAggregate imply that codegen must be enabled?

[JoshRosen]

Basically, I'm wondering if this is a bug. If this problem only occurs when mis-using GeneratedAggregate, then I think we should resolve this by adding an assertion / precondition check to GeneratedAggregate to ensure that codgen is enabled.

[JoshRosen]

@navis, can you comment on this?

[JoshRosen]

I've closed the JIRA issue as "invalid" since GeneratedAggregate will never be used when codegen is disabled. As a result, do you mind closing this issue? Thanks!

[JoshRosen]

Bump; can you please close this pull request? Thanks!