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https://issues.apache.org/jira/browse/PHOENIX-2154?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14700703#comment-14700703
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maghamravikiran commented on PHOENIX-2154:
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[~tdsilva] 
   How many reducers were running during these job executions? From your 
earlier mail in the mailing list, it looked like there was a single reducer 
writing the mapper output into HFile. The current implementation of 
HFileOutputFormat seems to determine the reducers based on the target table 
region count. If we can increase the region count of the target index table, we 
might see some speedup. 

> 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
>         Attachments: IndexTool.java
>
>
> 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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