[SPARK-44871][SQL][3.3] Fix percentile_disc behaviour #42611
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This PR fixes `percentile_disc()` function as currently it returns inforrect results in some cases. E.g.: ``` SELECT percentile_disc(0.0) WITHIN GROUP (ORDER BY a) as p0, percentile_disc(0.1) WITHIN GROUP (ORDER BY a) as p1, percentile_disc(0.2) WITHIN GROUP (ORDER BY a) as p2, percentile_disc(0.3) WITHIN GROUP (ORDER BY a) as p3, percentile_disc(0.4) WITHIN GROUP (ORDER BY a) as p4, percentile_disc(0.5) WITHIN GROUP (ORDER BY a) as p5, percentile_disc(0.6) WITHIN GROUP (ORDER BY a) as p6, percentile_disc(0.7) WITHIN GROUP (ORDER BY a) as p7, percentile_disc(0.8) WITHIN GROUP (ORDER BY a) as p8, percentile_disc(0.9) WITHIN GROUP (ORDER BY a) as p9, percentile_disc(1.0) WITHIN GROUP (ORDER BY a) as p10 FROM VALUES (0), (1), (2), (3), (4) AS v(a) ``` currently returns: ``` +---+---+---+---+---+---+---+---+---+---+---+ | p0| p1| p2| p3| p4| p5| p6| p7| p8| p9|p10| +---+---+---+---+---+---+---+---+---+---+---+ |0.0|0.0|0.0|1.0|1.0|2.0|2.0|2.0|3.0|3.0|4.0| +---+---+---+---+---+---+---+---+---+---+---+ ``` but after this PR it returns the correct: ``` +---+---+---+---+---+---+---+---+---+---+---+ | p0| p1| p2| p3| p4| p5| p6| p7| p8| p9|p10| +---+---+---+---+---+---+---+---+---+---+---+ |0.0|0.0|0.0|1.0|1.0|2.0|2.0|3.0|3.0|4.0|4.0| +---+---+---+---+---+---+---+---+---+---+---+ ``` Bugfix. Yes, fixes a correctness bug, but the old behaviour can be restored with `spark.sql.legacy.percentileDiscCalculation=true`. Added new UTs. Closes apache#42559 from peter-toth/SPARK-44871-fix-percentile-disc-behaviour. Authored-by: Peter Toth <peter.toth@gmail.com> Signed-off-by: Peter Toth <peter.toth@gmail.com>
MaxGekk
approved these changes
Aug 22, 2023
cloud-fan
approved these changes
Aug 22, 2023
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All GAs passed in fact. Merging to 3.3. |
MaxGekk
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Aug 23, 2023
### What changes were proposed in this pull request? This PR fixes `percentile_disc()` function as currently it returns inforrect results in some cases. E.g.: ``` SELECT percentile_disc(0.0) WITHIN GROUP (ORDER BY a) as p0, percentile_disc(0.1) WITHIN GROUP (ORDER BY a) as p1, percentile_disc(0.2) WITHIN GROUP (ORDER BY a) as p2, percentile_disc(0.3) WITHIN GROUP (ORDER BY a) as p3, percentile_disc(0.4) WITHIN GROUP (ORDER BY a) as p4, percentile_disc(0.5) WITHIN GROUP (ORDER BY a) as p5, percentile_disc(0.6) WITHIN GROUP (ORDER BY a) as p6, percentile_disc(0.7) WITHIN GROUP (ORDER BY a) as p7, percentile_disc(0.8) WITHIN GROUP (ORDER BY a) as p8, percentile_disc(0.9) WITHIN GROUP (ORDER BY a) as p9, percentile_disc(1.0) WITHIN GROUP (ORDER BY a) as p10 FROM VALUES (0), (1), (2), (3), (4) AS v(a) ``` currently returns: ``` +---+---+---+---+---+---+---+---+---+---+---+ | p0| p1| p2| p3| p4| p5| p6| p7| p8| p9|p10| +---+---+---+---+---+---+---+---+---+---+---+ |0.0|0.0|0.0|1.0|1.0|2.0|2.0|2.0|3.0|3.0|4.0| +---+---+---+---+---+---+---+---+---+---+---+ ``` but after this PR it returns the correct: ``` +---+---+---+---+---+---+---+---+---+---+---+ | p0| p1| p2| p3| p4| p5| p6| p7| p8| p9|p10| +---+---+---+---+---+---+---+---+---+---+---+ |0.0|0.0|0.0|1.0|1.0|2.0|2.0|3.0|3.0|4.0|4.0| +---+---+---+---+---+---+---+---+---+---+---+ ``` ### Why are the changes needed? Bugfix. ### Does this PR introduce _any_ user-facing change? Yes, fixes a correctness bug, but the old behaviour can be restored with `spark.sql.legacy.percentileDiscCalculation=true`. ### How was this patch tested? Added new UTs. Closes #42611 from peter-toth/SPARK-44871-fix-percentile-disc-behaviour-3.3. Authored-by: Peter Toth <peter.toth@gmail.com> Signed-off-by: Max Gekk <max.gekk@gmail.com>
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What changes were proposed in this pull request?
This PR fixes
percentile_disc()function as currently it returns inforrect results in some cases. E.g.:currently returns:
but after this PR it returns the correct:
Why are the changes needed?
Bugfix.
Does this PR introduce any user-facing change?
Yes, fixes a correctness bug, but the old behaviour can be restored with
spark.sql.legacy.percentileDiscCalculation=true.How was this patch tested?
Added new UTs.