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Posted to dev@hive.apache.org by "Jeff Hammerbacher (JIRA)" <ji...@apache.org> on 2009/03/03 22:52:56 UTC
[jira] Commented: (HIVE-318) [Hive] union all queries broken - all
kinds of problems
[ https://issues.apache.org/jira/browse/HIVE-318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12678466#action_12678466 ]
Jeff Hammerbacher commented on HIVE-318:
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Hey Namit,
Quick comment: would it be easier to track these issues if they were filed as separate tickets? Perhaps you are preparing a solution as a single patch, or they are all manifestations of the same root issue, but otherwise, this seems like a ticket that could be busted up.
Later,
Jeff
> [Hive] union all queries broken - all kinds of problems
> -------------------------------------------------------
>
> Key: HIVE-318
> URL: https://issues.apache.org/jira/browse/HIVE-318
> Project: Hadoop Hive
> Issue Type: Bug
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Namit Jain
>
> 1. Map-only job : same input
> Hangs because mapper tries to same open twice, and hadoop filesystem complains.
> Fix: Only initialize once - keep state at the Operator level for the same. Should do same for Close.
> 2. Map-only job : different inputs
> Loss of data due to rename.
> Fix: change rename to move files to the directory.
> 3. Map-only job in subquery + RedSink: works currently
> 4. 2 variables: so 4 sub-cases
> Number of sub-queries having map-reduce jobs. (1/2)
> Operator after Union (RS/FS)
>
> a. Number of sub-queries having map-reduce jobs. 1
> Operator after Union: RS
> Can be done in 2MR - really difficult with current infrastructure.
> Should do with 3 MR jobs now - break on top of UNION.
> Future optimization: move operators between Union and RS before Union.
> b. Number of sub-queries having map-reduce jobs. 2
> Operator after Union: RS
> Needs 3MR - Should do with 3 MR jobs - break on top of UNION.
> Future optimization: move operators between Union and RS before Union.
> c. Number of sub-queries having map-reduce jobs. 1
> Operator after Union: FS
> Can be done in 1MR - really difficult with current infrastructure.
> Can be easily done with 2 MR by removing UNION and cloning operators between Union and FS.
> Should do with 3 MR jobs now - break on top of UNION.
> Followup optimization: 2MR should be able to handle
> d. Number of sub-queries having map-reduce jobs. 2
> Operator after Union: FS
> Can be easily done with 2 MR by removing UNION and cloning operators between Union and FS.
> Should do with 3 MR jobs now - break on top of UNION.
> Followup optimization: 2MR should be able to handle
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