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https://issues.apache.org/jira/browse/CRUNCH-351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13910306#comment-13910306
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Chao Shi commented on CRUNCH-351:
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bq. with the idea of having a really small number of different keys so that
sorting the keys within each partition would require almost no processing.
I think I have missed something here. I guess there must be some optimization
in MR for such case. Could you explain more how this works?
bq. count = (++count % (numPartitions * 3));
Is it identical to "count = ++count % numPartitions", given the partition
function is "key % numPartitions"?
> Improve performance of Shard#shard on large records
> ---------------------------------------------------
>
> Key: CRUNCH-351
> URL: https://issues.apache.org/jira/browse/CRUNCH-351
> Project: Crunch
> Issue Type: Improvement
> Reporter: Chao Shi
> Assignee: Chao Shi
> Attachments: crunch-351-v2.patch, crunch-351.patch
>
>
> This avoids sorting on the input data, which may be long and make
> shuffle phase slow. The improvement is to sort on pseudo-random numbers.
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