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https://issues.apache.org/jira/browse/HIVE-20210?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jeffrey(Xilang) Yan updated HIVE-20210:
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Status: Patch Available (was: In Progress)
> Simple Fetch optimizer should lead to MapReduce when filter on non-partition
> column and conversion is minimal
> -------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-20210
> URL: https://issues.apache.org/jira/browse/HIVE-20210
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Affects Versions: 2.3.2, 2.3.1, 2.3.0
> Reporter: Jeffrey(Xilang) Yan
> Assignee: Jeffrey(Xilang) Yan
> Priority: Major
> Attachments: HIVE-20210.2.patch, HIVE-20210.patch
>
>
> When conversion is minimal, simple fetch can be used only when filter on
> partition column or no filter at all. But it lead to simple fetch even if
> filter on non-partition column. Unit test " select * from srcpart where key >
> 100 limit 10 " in the nonmr_fetch.q demonstration this issue – the unit test
> is not correct indeed(it should be Map Reduce but in test it is Simple
> Fetch).
> This issue lead to a serious problem when data size is huge. When conversion
> is more and filter on both partition column and non-partition column, it will
> not chech hive.fetch.task.conversion.threshold, which lead to the query to
> takes hours to finish. This issue doesn't exist in 1.2.1, how it works should
> be a magic...
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