[HIVE-6439] Introduce CBO step in Semantic Analyzer

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Assignee: Harish Butani
• Reporter: Harish Butani
• Created: 15/Feb/14 21:32
• Updated: 24/Jun/14 21:41
• Resolved: 24/Jun/14 21:41

Description

This patch introduces CBO step in SemanticAnalyzer. For now the CostBasedOptimizer is an empty shell.
The contract between SemAly and CBO is:

• CBO step is controlled by the 'hive.enable.cbo.flag'.
• When true Hive SemAly will hand CBO a Hive Operator tree (with operators annotated with stats). If it can CBO will return a better plan in Hive AST form.