Stamatis Zampetakis created HIVE-25816:
------------------------------------------
Summary: Log CBO plan after rule application for debugging purposes
Key: HIVE-25816
URL: https://issues.apache.org/jira/browse/HIVE-25816
Project: Hive
Issue Type: Task
Components: CBO
Reporter: Stamatis Zampetakis
Assignee: Stamatis Zampetakis
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|https://github.com/apache/calcite/blob/e04f3b08dcfb6910ff4df3810772c346b25ed424/core/src/main/java/org/apache/calcite/plan/AbstractRelOptPlanner.java#L367]
and
[VolcanoPlanner|https://github.com/apache/calcite/blob/e04f3b08dcfb6910ff4df3810772c346b25ed424/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoRuleCall.java#L126]
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.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
