[IMPALA-8182] Extend PlanCtx to provide access to the entire internal plan

• Type: Improvement
• Status: In Progress
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: Impala 3.1.0
• Component/s: Frontend
• Epic Color: ghx-label-9
• Assignee: Unassigned
• Reporter: Paul Rogers
• Created: 11/Feb/19 17:19
• Updated: 05/Oct/19 21:12

Description

Historically, the Impala planner is a function: AST in one end, Thrift plan out the other. The planner itself creates a rich intermediate plan representation, but none of those objects were available for testing, forcing all tests, no matter how detailed, to run as end-to-end tests: SQL in one end, verify a (very abbreviated) DESCRIBE output out the other.

A recent change introduced the PlanCtx that provided access to the parallelized plan fragments. Doing so allowed adding a variety of cardinality tests.

It turns out that additional testing requires access to the "single node plan" in order to verify things like join cardinality.

This ticket asks to modify the PlanCtx to capture all the internal plan nodes: both single node and distributed, to enable full unit testing.