Stamatis Zampetakis created HIVE-29380:
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Summary: Drop synthetic HiveProject and
HiveFilterProjectTSTransposeRule
Key: HIVE-29380
URL: https://issues.apache.org/jira/browse/HIVE-29380
Project: Hive
Issue Type: Task
Reporter: Stamatis Zampetakis
Assignee: Stamatis Zampetakis
The [synthetic indicator in
HiveProject|https://github.com/apache/hive/blob/ee7138bf7a1a1ee1de07fa2243fe947a627268cb/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/reloperators/HiveProject.java#L49]
was introduced alongside HiveFilterProjectTSTransposeRule in HIVE-11110 as way
to restrict the application of project pushdown (PPD) to a limited number of
cases. The rule was made to apply only on projections directly over a table
scan that have been introduced after field trimming.
In fact, the synthetic indicator is completely redundant since if we restrict
the rule matches strictly to projections over table scans we can have the same
outcome without the need to maintain an explicit indicator that specializes the
behavior of the projection operator.
Dropping the redundant logic and rule reduces code maintenance and tech-debt
and facilitates the detection of equivalent expressions/plans since there are
no multiple versions of a project operator.
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