Re: Pig reduce :: NullPointerException

Wed, 26 Sep 2007 11:12:47 -0700

It's hard to debug this at the moment, as the current code that handles this has been entirely rewritten. Pig is in the process of becoming an incubator project in Apache (see http://wiki.apache.org/incubator/PigProposal). Once that is out you will have access to pig code that fixes this bug. 

Alan.

bhupesh bansal wrote:

I am trying to use SubGroup and Flatten constructs, I get this Null pointer
exception
Queries: 
table1 = Load 'datafile' using PigStorage(' ') as (sid, eid, mid, pid, did,
fid);
table2  = Load 'datafile2' using PigStorage(' ') as (src_d, dest_d,
score_d);

table3 = COGROUP table1 by did INNER, table2 by src_d INNER;
table4 = FOREACH table3 GENERATE FLATTEN(table1), FLATTEN(table2);
store table4 'table4.txt'

Error in File : /task_0002_r_000006_1/stderr/part-000000

main: Executing driver on (100310770, {(100310770, 42611676, 101703187, 54,
61661798, 579874705)[0], (100310770, 492859788, 301826791, 16573, 61661798,
579874705)[0], (100310770, 91343671, 68965026, 26215, 790, 1705)[0],
(100310770, 138450842, 112796472, 29238, 61661798, 579874705)[0]}, {(100310770, 
138450842, 112796472, 29238, 61661798, 579874705)[1], (100310770, 492859788,
301826791, 16573, 61661798, 579874705)[1], (100310770, 91343671, 68965026,
26215, 790, 1
705)[1], (100310770, 42611676, 101703187, 54, 61661798, 579874705)[1]})
java.lang.NullPointerException
        at com.yahoo.pig.impl.eval.EvalItemList.eval(EvalItemList.java:292)
        at
com.yahoo.pig.impl.eval.EvalItemList.access$000(EvalItemList.java:22)
        at com.yahoo.pig.impl.eval.EvalItemList$1.add(EvalItemList.java:75)
        at
com.yahoo.pig.impl.mapreduceExec.PigMapReduce.reduce(PigMapReduce.java:133)
        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:313)
        at
org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1445)

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