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https://issues.apache.org/jira/browse/HIVE-5921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13839687#comment-13839687
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Harish Butani commented on HIVE-5921:
-------------------------------------
+1
subject to all tests passing
> Better heuristics for worst case statistics estimates for join, limit and
> filter operator
> -----------------------------------------------------------------------------------------
>
> Key: HIVE-5921
> URL: https://issues.apache.org/jira/browse/HIVE-5921
> Project: Hive
> Issue Type: Sub-task
> Components: Query Processor, Statistics
> Affects Versions: 0.13.0
> Reporter: Prasanth J
> Assignee: Prasanth J
> Fix For: 0.13.0
>
> Attachments: HIVE-5921.1.patch, HIVE-5921.2.patch, HIVE-5921.3.patch,
> HIVE-5921.4.patch
>
>
> This is a subtask of HIVE-5369. In worst case (i.e; absence of column
> statistics) HIVE-5849 improved the basic statistics with heuristics. But the
> heuristics failed to provide better estimates in few cases. For example:
> FILTER operator heuristics did not take into account the number of predicates
> and if the predicate contains partition column. Also, JOIN estimates were too
> aggressive and was not user configurable.
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