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https://issues.apache.org/jira/browse/PIG-2237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13093309#comment-13093309
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jirapos...@reviews.apache.org commented on PIG-2237:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/1664/
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(Updated 2011-08-29 23:34:23.448085)
Review request for pig and Thejas Nair.
Summary
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See PIG-2237
This addresses bug PIG-2237.
https://issues.apache.org/jira/browse/PIG-2237
Diffs (updated)
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trunk/src/org/apache/pig/backend/hadoop/executionengine/mapReduceLayer/LimitAdjuster.java
PRE-CREATION
trunk/src/org/apache/pig/backend/hadoop/executionengine/mapReduceLayer/MRCompiler.java
1162260
trunk/src/org/apache/pig/backend/hadoop/executionengine/mapReduceLayer/MRUtil.java
PRE-CREATION
trunk/src/org/apache/pig/backend/hadoop/executionengine/mapReduceLayer/MapReduceLauncher.java
1162260
trunk/test/org/apache/pig/test/TestEvalPipeline2.java 1162260
trunk/test/org/apache/pig/test/TestMRCompiler.java 1162260
Diff: https://reviews.apache.org/r/1664/diff
Testing
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Test-patch:
[exec] +1 overall.
[exec]
[exec] +1 @author. The patch does not contain any @author tags.
[exec]
[exec] +1 tests included. The patch appears to include 3 new or
modified tests.
[exec]
[exec] +1 javadoc. The javadoc tool did not generate any warning
messages.
[exec]
[exec] +1 javac. The applied patch does not increase the total number
of javac compiler warnings.
[exec]
[exec] +1 findbugs. The patch does not introduce any new Findbugs
warnings.
[exec]
[exec] +1 release audit. The applied patch does not increase the
total number of release audit warnings.
Unit test:
all pass.
Thanks,
Daniel
> LIMIT generates wrong number of records if pig determines no of reducers as
> more than 1
> ---------------------------------------------------------------------------------------
>
> Key: PIG-2237
> URL: https://issues.apache.org/jira/browse/PIG-2237
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.8.0, 0.9.0
> Reporter: Anitha Raju
> Assignee: Daniel Dai
> Fix For: 0.9.1, 0.10
>
> Attachments: PIG-2237-1.patch, PIG-2237-2.patch, PIG-2237-3.patch
>
>
> Hi,
> For a script
> ========
> A = load 'test.txt' using PigStorage() as (a:int,b:int);
> B = order A by a ;
> C = limit B 2;
> store C into 'op1' using PigStorage();
> ========
> Limit and ORDER BY are done in the same MR job if no explicit PARALLELism is
> mentioned.
> In this case, the no of reducers are determined by pig and sometimes it is
> calculated > 1.
> Since limit happens at the reduce side, each reduce tasks does a limit
> separately generating n*2 records where n is the no of reduce tasks
> calculated by pig.
> If an explicit specification of no of reduce tasks using PARALLEL keyword is
> done on ORDER BY,
> ==========
> B = order A by a PARALLEL 4;
> ==========
> another MR is created with 1 reduce task where the limit is done.
> In short, the issue occurs when the no of reducers calculated by pig is
> greater than 1 and a limit is involved in the MR.
> The issue can be replicated by specifying
> ==========
> -Dpig.exec.reducers.bytes.per.reducer
> ==========
> The issue is seen in 0.8 and 0.9 version. It works good in 0.7
> Regards,
> Anitha
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