[TAJO-481] Logical plan refactoring

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.8.0
• Component/s: distributed query plan, Planner/Optimizer
• Assignee: Jihoon Son
• Reporter: Jihoon Son
• Created: 07/Jan/14 09:27
• Updated: 08/Jan/14 14:52

Description

The current logical plan has some problems such as requiring a complex logic to make a master plan, hard to be extended to support multiple outputs, and inefficient de/serialization.
In this issue, we improve the logical plan to handle these problems. We should reflect the followings.

• Change the logical plan from tree to DAG to easily support multiple outputs
• Enable to connect logical nodes and data channels
  • This makes GlobalPlanner simpler, since it removes complex codes for scan node creation.
  • Data channel has two types of materialized data channel and stream data channel (for the future). The materialized data channel should contain the store information for sender and the scan information for receiver.
• Refactor the de/serialization of logical plan
• Add a compare tool and hash tool for logical nodes
  • During the query planning, logical nodes are compared and hashed in various ways. To support various comparison and hashing, we need a new class such as LogicalNodeComparator and LogicalNodeHashCoder