Stamatis Zampetakis created HIVE-29250:
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Summary: Display effects of PlanModifierForASTConv in EXPLAIN CBO
output
Key: HIVE-29250
URL: https://issues.apache.org/jira/browse/HIVE-29250
Project: Hive
Issue Type: Improvement
Components: CBO
Reporter: Stamatis Zampetakis
Assignee: Stamatis Zampetakis
The EXPLAIN CBO clause outputs the plan generated by the cost-based (Calcite)
optimizer. Although it is not explicitly defined which state of the CBO plan
should be displayed to the end-users someone would expect that it is the final
plan after applying all kind of transformations that are relevant and can
affect the shape of the physical plan.
However, at the moment the transformations that happen inside
PlanModifierForASTConv are not *always* reflected to the plan. These
transformations are important cause they can affect the physical plan both in
terms of correctness and performance. Some transformations from
PlanModifierForASTConv are already visible mostly as a side-effect of modifying
directly the object reference that is passed as input.
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