[SPARK-12767] Improve conditional expressions

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: Optimizer, SQL
• Target Version/s: 2.0.0
• Assignee: Reynold Xin
• Reporter: Reynold Xin
• Created: 12/Jan/16 07:54
• Updated: 23/Mar/16 04:17
• Resolved: 23/Mar/16 04:17

Description

There are a few improvements we can do to improve conditional expressions. This ticket tracks them.

Sub-Tasks

• Add unit test for simplifying if expression: Resolved
• Remove CaseKeyWhen expression: Resolved
• Simplify CaseWhen by breaking "branches" into "conditions" and "values": Resolved
• Implement rules for branch elimination for CaseWhen in SimplifyConditionals: Resolved
• Remove If expression: Closed
• Improve code generation for CaseWhen: Resolved