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https://issues.apache.org/jira/browse/PIG-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15105596#comment-15105596
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Rohini Palaniswamy edited comment on PIG-4587 at 1/18/16 6:02 PM:
------------------------------------------------------------------
Changes done:
- Now adding isFirstReduceOfKey only for right outer join
- Additional enhancements to stats display which helped debug the issue
faster instead of having to go to the UI
-Added REDUCE_INPUT_RECORDS counter in the stats output which
contains the shuffle records. INPUT_RECORDS_PROCESSED only contains broadcast
and MR input.
-InputRecords and OutputRecords were showing 0 if there was no load
or store.
was (Author: rohini):
Changes done:
- Now adding isFirstReduceOfKey only for right outer join
- Additional enhancements to stats display which helped debug the issue
faster instead of having to go to the UI
- Added REDUCE_INPUT_RECORDS counter in the stats output which
contains the shuffle records. INPUT_RECORDS_PROCESSED only contains broadcast
and MR input.
- InputRecords and OutputRecords were showing 0 if there was no
load or store.
> Applying isFirstReduceOfKey for Skewed left outer join skips records
> --------------------------------------------------------------------
>
> Key: PIG-4587
> URL: https://issues.apache.org/jira/browse/PIG-4587
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.15.0
> Reporter: Rohini Palaniswamy
> Assignee: Daniel Dai
> Priority: Critical
> Fix For: 0.16.0
>
> Attachments: PIG-4587-1.patch
>
>
> PIG-4377 introduced isFirstReduceOfKey to avoid extra records in case of over
> sampling. But the issue can occur only in the case of right outer join. But
> it is added to the plan in MRCompiler and TezCompiler (PIG-4580) for both
> left and right outer joins. We need to remove that extra check for right
> outer join. It is unnecessary performance penalty.
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