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https://issues.apache.org/jira/browse/PIG-1144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12788447#action_12788447
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Daniel Dai commented on PIG-1144:
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I find the root cause of the problem. For every sort job, we hard code
parallelism as 1 if user do not use PARALLEL keyword. We shall leave
parallelism as -1 in this case, and then the later code will find it and use
default_parallel value instead.
> set default_parallelism construct does not set the number of reducers
> correctly
> -------------------------------------------------------------------------------
>
> Key: PIG-1144
> URL: https://issues.apache.org/jira/browse/PIG-1144
> Project: Pig
> Issue Type: Bug
> Components: impl
> Affects Versions: 0.7.0
> Environment: Hadoop 20 cluster with multi-node installation
> Reporter: Viraj Bhat
> Fix For: 0.7.0
>
> Attachments: brokenparallel.out, genericscript_broken_parallel.pig
>
>
> Hi all,
> I have a Pig script where I set the parallelism using the following set
> construct: "set default_parallel 100" . I modified the "MRPrinter.java" to
> printout the parallelism
> {code}
> ...
> public void visitMROp(MapReduceOper mr)
> mStream.println("MapReduce node " + mr.getOperatorKey().toString() + "
> Parallelism " + mr.getRequestedParallelism());
> ...
> {code}
> When I run an explain on the script, I see that the last job which does the
> actual sort, runs as a single reducer job. This can be corrected, by adding
> the PARALLEL keyword in front of the ORDER BY.
> Attaching the script and the explain output
> Viraj
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