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Posted to mapreduce-issues@hadoop.apache.org by "Owen O'Malley (JIRA)" <ji...@apache.org> on 2012/08/01 20:58:02 UTC
[jira] [Created] (MAPREDUCE-4505) Create a combiner bypass path for
keys with a single value
Owen O'Malley created MAPREDUCE-4505:
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Summary: Create a combiner bypass path for keys with a single value
Key: MAPREDUCE-4505
URL: https://issues.apache.org/jira/browse/MAPREDUCE-4505
Project: Hadoop Map/Reduce
Issue Type: Bug
Components: performance, task
Reporter: Owen O'Malley
It would help optimize a lot of cases where there aren't a lot of replicated keys if the framework would bypass the deserialize/combiner/serialize step for keys that only have a single value.
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[jira] [Assigned] (MAPREDUCE-4505) Create a combiner bypass path
for keys with a single value
Posted by "Owen O'Malley (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/MAPREDUCE-4505?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Owen O'Malley reassigned MAPREDUCE-4505:
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Assignee: Arun C Murthy
> Create a combiner bypass path for keys with a single value
> ----------------------------------------------------------
>
> Key: MAPREDUCE-4505
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4505
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: performance, task
> Reporter: Owen O'Malley
> Assignee: Arun C Murthy
>
> It would help optimize a lot of cases where there aren't a lot of replicated keys if the framework would bypass the deserialize/combiner/serialize step for keys that only have a single value.
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[jira] [Commented] (MAPREDUCE-4505) Create a combiner bypass path
for keys with a single value
Posted by "Karthik Kambatla (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/MAPREDUCE-4505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13426827#comment-13426827 ]
Karthik Kambatla commented on MAPREDUCE-4505:
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Given the overheads involved, it might not be a bad idea to skip the combiner for more than just a single value. The threshold for running the combiner can be number of values or a cumulative size of the values.
> Create a combiner bypass path for keys with a single value
> ----------------------------------------------------------
>
> Key: MAPREDUCE-4505
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4505
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: performance, task
> Reporter: Owen O'Malley
> Assignee: Arun C Murthy
>
> It would help optimize a lot of cases where there aren't a lot of replicated keys if the framework would bypass the deserialize/combiner/serialize step for keys that only have a single value.
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