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From "Matthew Hayes (JIRA)" <j...@apache.org>
Subject [jira] [Closed] (DATAFU-11) ReservoirSample does not behave as expected when grouping by a key other than ALL
Date Thu, 06 Mar 2014 04:58:44 GMT

     [ https://issues.apache.org/jira/browse/DATAFU-11?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Matthew Hayes closed DATAFU-11.
-------------------------------


> ReservoirSample does not behave as expected when grouping by a key other than ALL
> ---------------------------------------------------------------------------------
>
>                 Key: DATAFU-11
>                 URL: https://issues.apache.org/jira/browse/DATAFU-11
>             Project: DataFu
>          Issue Type: Bug
>            Reporter: Will Vaughan
>            Assignee: Matthew Hayes
>             Fix For: 1.3.0
>
>         Attachments: DATAFU-11-v2.patch, DATAFU-11.patch
>
>
> Reported by Barbara Mucha ([Issue #92 on GitHub|https://github.com/linkedin/datafu/issues/92]):
> ReservoirSample does not behave as expected when grouping by a key other than ALL.
> It appears like the sample is done on the full input instead of the group input.
> Given input:
> {noformat}
> a1,5
> a1,6
> a1,7
> a2,5
> a2,6
> a2,7
> {noformat}
> with the following program
> {noformat}
> DEFINE ReservoirSample datafu.pig.sampling.ReservoirSample('2');
> data = LOAD 'input.txt' USING PigStorage(',') AS (key: chararray, value: chararray);
> grouped = GROUP data BY key;
> sample2 = FOREACH grouped GENERATE ReservoirSample(data);
> {noformat}
> the expected output should be similar to
> {noformat}
> (a1, {(a1,5),(a1,7)}
> (a2, {(a2,5),(a2,7)}
> {noformat}
> However, actual output may show up as
> {noformat}
> (a1, {(a1,5),(a1,7)}
> (a2, {(a1,5),(a1,7)}
> {noformat}



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