[HIVE-25816] Log CBO plan after rule application for debugging purposes

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0-alpha-1
• Component/s: CBO
• Labels: pull-request-available
• Assignee: Stamatis Zampetakis
• Reporter: Stamatis Zampetakis
• Created: 16/Dec/21 14:24
• Updated: 17/Nov/22 08:48
• Resolved: 22/Dec/21 14:48

Description

In many cases, we want to identify which rule lead to a certain transformation in the plan or need to observe how the query plan evolves by applying some rules in order to fix some bug or find the right place to introduce another optimization step.

Currently there are some logs during the application of a rule triggered by the HepPlanner and VolcanoPlanner but they more or less display only the top operator of the transformation and not the whole subtree.

It would help if instead of displaying only the top operator we logged the equivalent of EXPLAIN CBO on the transformed sub-tree. 

The change is going to be introduced soon by default in Calcite (CALCITE-4704) but till we update to that version it would help to have this functionality already in Hive.

For more examples about the proposed change have a look in CALCITE-4704.

Issue Links

• is related to: HIVE-25884 Improve rule description for rules defined as subclasses
• relates to: CALCITE-4704 Log produced plan after rule application using explain formatting
• links to: GitHub Pull Request #2887