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https://issues.apache.org/jira/browse/KYLIN-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16851727#comment-16851727
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ASF subversion and git services commented on KYLIN-2620:
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Commit 670c2a98a82a699481eceddb685168104d5b185c in kylin's branch
refs/heads/master from chao long
[ https://gitbox.apache.org/repos/asf?p=kylin.git;h=670c2a9 ]
KYLIN-2620 TopN can't match when multi sort columns
> Check for "ORDER BY LIMIT" clause when rewrite SUM query as TOPN
> ----------------------------------------------------------------
>
> Key: KYLIN-2620
> URL: https://issues.apache.org/jira/browse/KYLIN-2620
> Project: Kylin
> Issue Type: Bug
> Components: Measure - TopN
> Reporter: Lin Tingmao
> Assignee: Chao Long
> Priority: Major
> Fix For: v3.0.0, v2.6.3
>
> Attachments: cube_desc.png, sql.png
>
>
> When running the following query
> select sum(measure) from table group by col_id
> if there exists TOPN(measure, group by col_id) measure,
> TopNMeasureType.isTopNCompatibleSum() will pass, so the SUM is rewritten
> to TOPN. This confuses the user since they may expect a accurate result for
> every distinct value of group by column(s).
> Kylin should check if "ORDER BY col_id LIMIT topncapacity" is present in the
> query to determine whether to rewrite.
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