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https://issues.apache.org/jira/browse/CRUNCH-351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13909737#comment-13909737
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Chao Shi commented on CRUNCH-351:
---------------------------------
bq. About the use of the random long as the key, I was thinking it might be
even better to use a limited-range int as the generated key..
OK, let me switch to int32.
bq. Also on the subject of the random key generation, is there any drawback to
using a constant value as the seed for the Random? If not, it might be better
to just use a constant to avoid the dependency on the MapReduce framework.
I think a constant random seed is effectively same as using a increasing key
and passing records to reducers in round-robin. The general drawback is that
all mapper will produce the same sequence. For this particular problem, I think
using the round-robin approach is OK and simpler.
> 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.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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