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https://issues.apache.org/jira/browse/IMPALA-13781?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joe McDonnell resolved IMPALA-13781.
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Fix Version/s: Impala 4.6.0
Resolution: Fixed
> report_benchmark_result.py uses the wrong calculation for median diff %
> -----------------------------------------------------------------------
>
> Key: IMPALA-13781
> URL: https://issues.apache.org/jira/browse/IMPALA-13781
> Project: IMPALA
> Issue Type: Bug
> Components: Infrastructure
> Affects Versions: Impala 4.6.0
> Reporter: Joe McDonnell
> Assignee: Joe McDonnell
> Priority: Major
> Fix For: Impala 4.6.0
>
>
> The benchmark report includes a column with the "Median Diff(%)", but it is
> being calculated improperly. It can produce % reductions greater than 100%
> because it is dividing by the new result rather than the base result:
> {noformat}
> # median uses "results", but it should use "ref_results"
> median = results[SORTED][int(len(results[SORTED]) / 2)]
> all_diffs = [x - y for x in results[SORTED] for y in
> ref_results[SORTED]]
> all_diffs.sort()
> self.median_diff = all_diffs[int(len(all_diffs) / 2)] /
> median{noformat}
> In an AB test, the median variable used as the divisor should be the A value
> (i.e. the base / reference value). Instead, this is using the B value.
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