[SPARK-39989][SQL] Support estimate column statistics if it is foldable expression #37421
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HyukjinKwon
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Aug 8, 2022
dongjoon-hyun
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Aug 8, 2022
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Thank you, @wangyum , @beliefer , @HyukjinKwon . |
wangyum
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May 26, 2023
…tistics if it is foldable expression (#1031) ### What changes were proposed in this pull request? This PR adds support estimate column statistics if it is foldable expression. For example: estimate the `'a' AS a`'s column statistics from `SELECT 'a' AS a FROM tbl`. 1. If the foldable expression is null: ```scala ColumnStat(Some(0), None, None, Some(rowCount), Some(size), Some(size), None, 2) ``` 2. If the foldable expression is not null: ```scala ColumnStat(Some(1), Some(value), Some(value), Some(0), Some(size), Some(size), None, 2) ``` ### Why are the changes needed? Improve column statistics. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? Unit test. Closes #37421 from wangyum/SPARK-39989. Lead-authored-by: Yuming Wang <yumwang@ebay.com> Co-authored-by: Yuming Wang <wgyumg@gmail.com> Signed-off-by: Dongjoon Hyun <dongjoon@apache.org> (cherry picked from commit d77bc70)
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What changes were proposed in this pull request?
This PR adds support estimate column statistics if it is foldable expression. For example: estimate the
'a' AS a's column statistics fromSELECT 'a' AS a FROM tbl.Why are the changes needed?
Improve column statistics.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
Unit test.