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https://issues.apache.org/jira/browse/HIVE-5849?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Prasanth J updated HIVE-5849:
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Attachment: HIVE-5849.6.patch
Fixed failing test cases. Most failures were due to NPE in new code which is
fixed now. union20.q query failed because subquery with UNION ALL does not
propagate the table alias properly. This will return null column statistics
though valid column statistics are present. This issue will be addressed in a
separate JIRA.
> Improve the stats of operators based on heuristics in the absence of any
> column statistics
> ------------------------------------------------------------------------------------------
>
> Key: HIVE-5849
> URL: https://issues.apache.org/jira/browse/HIVE-5849
> Project: Hive
> Issue Type: Sub-task
> Components: Query Processor, Statistics
> Reporter: Prasanth J
> Assignee: Prasanth J
> Fix For: 0.13.0
>
> Attachments: HIVE-5849.1.patch.txt, HIVE-5849.2.patch.txt,
> HIVE-5849.3.patch, HIVE-5849.3.patch.txt, HIVE-5849.4.javaonly.patch,
> HIVE-5849.5.patch, HIVE-5849.6.patch
>
>
> In the absence of any column statistics, operators will simply use the
> statistics from its parents. It is useful to apply some heuristics to update
> basic statistics (number of rows and data size) in the absence of any column
> statistics. This will be worst case scenario.
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