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Posted to dev@hive.apache.org by "Prasanth J (JIRA)" <ji...@apache.org> on 2013/12/03 20:49:36 UTC
[jira] [Updated] (HIVE-5921) Better heuristics for worst case
statistics estimates for join, limit and filter operator
[ https://issues.apache.org/jira/browse/HIVE-5921?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Prasanth J updated HIVE-5921:
-----------------------------
Attachment: HIVE-5921.1.patch
> 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
>
>
> 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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