You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@datafu.apache.org by "Matthew Hayes (JIRA)" <ji...@apache.org> on 2014/01/17 23:30:20 UTC
[jira] [Updated] (DATAFU-11) ReservoirSample does not behave as
expected when grouping by a key other than ALL
[ https://issues.apache.org/jira/browse/DATAFU-11?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Matthew Hayes updated DATAFU-11:
--------------------------------
Description:
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}
was:
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:
a1,5
a1,6
a1,7
a2,5
a2,6
a2,7
with the following program
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);
the expected output should be similar to
(a1, {(a1,5),(a1,7)}
(a2, {(a2,5),(a2,7)}
However, actual output may show up as
(a1, {(a1,5),(a1,7)}
(a2, {(a1,5),(a1,7)}
> 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
>
> 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}
--
This message was sent by Atlassian JIRA
(v6.1.5#6160)