HIVE-29627 IS_NULL selectivity improvement with stats#6553
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cyanzheng2926 wants to merge 6 commits into
Open
HIVE-29627 IS_NULL selectivity improvement with stats#6553cyanzheng2926 wants to merge 6 commits into
cyanzheng2926 wants to merge 6 commits into
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Pull request overview
Improves Hive’s Calcite-based filter selectivity estimation for IS NULL predicates by using existing column null-count statistics when available, falling back to the default selectivity when stats are missing/estimated.
Changes:
- Add dedicated
IS_NULLselectivity handling inFilterSelectivityEstimatorthat usesnumNullsstats forHiveTableScan. - Add helper logic to detect missing/estimated column stats and fall back to
DEFAULT_COMPARISON_SELECTIVITY. - Add unit tests covering
IS NULLselectivity with valid stats, missing stats, and estimated-stats fallback.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/stats/FilterSelectivityEstimator.java |
Adds IS_NULL selectivity computation using column null statistics plus a missing/estimated-stats fallback helper. |
ql/src/test/org/apache/hadoop/hive/ql/optimizer/calcite/stats/TestFilterSelectivityEstimator.java |
Adds unit tests validating IS NULL selectivity behavior under different stats availability scenarios. |
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…ange & refactored based on commit review & added null test
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asf-ci-hive
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tests unstable
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What changes were proposed in this pull request?
This PR is for issues.apache.org/jira/browse/HIVE-29627 which tries to improve the IS_NULL selectivity with exisiting statistics.
Why are the changes needed?
To improve the selectivity of IS_NULL with stats instead of falling to the default path in the switch statement.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
Added unit tests under TestFilterSelectivityEstimator.java