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https://issues.apache.org/jira/browse/PHOENIX-2154?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14704376#comment-14704376
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Samarth Jain commented on PHOENIX-2154:
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Reducers could start running before all the mappers are complete. However, the
reduce step in a reducer is not executed till all the mappers are done. Ravi,
it looks like you are updating the index state in the setUp method. Do you know
when is setUp executed? Is it executed before the shuffle phase of a reducer?
If yes, it probably makes sense to move the code you have in setUp to the
reduce method instead.
> Failure of one mapper should not affect other mappers in MR index build
> -----------------------------------------------------------------------
>
> Key: PHOENIX-2154
> URL: https://issues.apache.org/jira/browse/PHOENIX-2154
> Project: Phoenix
> Issue Type: Bug
> Reporter: James Taylor
> Assignee: maghamravikiran
> Attachments: IndexTool.java, PHOENIX-2154-WIP.patch
>
>
> Once a mapper in the MR index job succeeds, it should not need to be re-done
> in the event of the failure of one of the other mappers. The initial
> population of an index is based on a snapshot in time, so new rows getting
> *after* the index build has started and/or failed do not impact it.
> Also, there's a 1:1 correspondence between index rows and table rows, so
> there's really no need to dedup. However, the index rows will have a
> different row key than the data table, so I'm not sure how the HFiles are
> split. Will they potentially overlap and is this an issue?
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