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https://issues.apache.org/jira/browse/HIVE-1007?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12879206#action_12879206
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Dave Lerman commented on HIVE-1007:
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Tried the steps above on Hadoop 0.20.2. It still logs "number of splits 0",
but instead of hanging at 0%, it completes the map, then fails with a "Shuffle
Error: Exceeded MAX_FAILED_UNIQUE_FETCHES; bailing-out." in the reduce. This
is clearly preferable to hanging and doesn't seem like a totally unreasonable
result when asking for data from an empty file -- should I close the ticket?
> CombinedHiveInputFormat fails with empty input
> ----------------------------------------------
>
> Key: HIVE-1007
> URL: https://issues.apache.org/jira/browse/HIVE-1007
> Project: Hadoop Hive
> Issue Type: Bug
> Components: Query Processor
> Affects Versions: 0.4.1
> Reporter: Dave Lerman
> Assignee: Dave Lerman
> Attachments: hive.1007.1.patch
>
>
> In a multi-stage query, when one stage returns no data (resulting in a bunch
> of output files with size 0), the next stage creates a job with 0 mappers
> which just sits in the Hadoop task track forever and hangs the query at 0%.
> The issue is that CombineHiveInputFormat looks for blocks to populate splits,
> find nones (since input is all 0 bytes), and then returns an empty array from
> getSplits.
> There may be good a way to just skip that job altogether, but as a quick hack
> to get it working, when there are no splits, I just create a single empty one
> using the first path so that the job doesn't hang.
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