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https://issues.apache.org/jira/browse/HIVE-15397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15736905#comment-15736905
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Sergey Shelukhin commented on HIVE-15397:
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Btw, I am too lazy to rerun it again now, but I think the current master is
inconsistent, cause the out file changes that removed the rows on the first run
removed the rows because I disabled metadata-only by default. So, non-optimized
path on master doesn't return such rows, but metadata-only does return them.
After the patch, neither does.
> metadata-only queries may return incorrect results with empty tables
> --------------------------------------------------------------------
>
> Key: HIVE-15397
> URL: https://issues.apache.org/jira/browse/HIVE-15397
> Project: Hive
> Issue Type: Bug
> Reporter: Sergey Shelukhin
> Assignee: Sergey Shelukhin
> Attachments: HIVE-15397.01.patch, HIVE-15397.patch
>
>
> Queries like select 1=1 from t group by 1=1 may return rows, based on
> OneNullRowInputFormat, even if the source table is empty. For now, add some
> basic detection of empty tables and turn this off by default (since we can't
> know whether a table is empty or not based on there being some files, without
> reading them).
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