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https://issues.apache.org/jira/browse/HIVE-14590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15431305#comment-15431305
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Ashutosh Chauhan commented on HIVE-14590:
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Problem is outerQueryLimit field is used to indicate limit on query. As a
result fetch operator only fetches those many rows. Assume query is like (subq1
limit 5) union (subq2 limit 5). Because of this bug limit in subquery becomes
global limit of 5 and instead of 10 rows only 5 are fetched.
In the proposed fix, during Union operator conversion we check if there is any
limit operator in subtree and clear out this outqueryLimit in such a case.
> CBO (Calcite Return Path) Incorrect result set when limit is present in one
> of the union branches
> -------------------------------------------------------------------------------------------------
>
> Key: HIVE-14590
> URL: https://issues.apache.org/jira/browse/HIVE-14590
> Project: Hive
> Issue Type: Sub-task
> Components: Logical Optimizer
> Affects Versions: 2.0.0, 2.1.0
> Reporter: Ashutosh Chauhan
> Assignee: Ashutosh Chauhan
> Attachments: HIVE-14590.patch
>
>
> Limit gets propagated outside union.
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