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Pig, mail # user - Correlation function out of memory error


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Correlation function out of memory error
Houssam H. 2013-02-21, 19:39
Hi,

I have a file with a few hundreds of columns with doubles and I am
interested in creating a correlation matrix for the columns:

A = load 'myData' using PigStorage(':');
B = group A all;
D = foreach B generate group,COR(A.$0,A.$1,A.$2);

For N parameters, the COR function will generate N(N-1)/2 correlations.
This is fine as long as N is less than 100: COR(A.$0,A.$1, .... A.$100);
However once N is more than 100 or 200 I have an out of memory error (of
course this would depend on the amount of RAM you have):

883 [main] ERROR org.apache.pig.tools.pigstats.SimplePigStats - ERROR
6016: Out of memory.
893 [main] ERROR org.apache.pig.tools.pigstats.PigStatsUtil - 1 map
reduce job(s) failed!

My file is less than 50Mb, so pig is running all the time with only one mapper.

This behavior was the same whether I run the script locally (pig -x
local) or on Amazon ElasticMapReduce with multiple instances assigned
to the job.

Is there a solution to be able to run the correlation function for a
big number of parameters?

Thank you in advance!

-Houssam
+
Johnny Zhang 2013-02-22, 22:18
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Johnny Zhang 2013-02-22, 23:04
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Johnny Zhang 2013-02-23, 03:10
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Houssam 2013-02-25, 08:30