Another possible reason,

if namenode is in safemode, this error happens. 

Thanks
-- Prasanth

On Aug 29, 2012, at 2:47 AM, Dmitriy Ryaboy <[email protected]> wrote:

> Please take a look at your job tracker page. It will have a failed job, which 
> will have failed tasks, which will have more detailed error logs. 
> 
> On Aug 28, 2012, at 5:52 PM, Mohit Anchlia <[email protected]> wrote:
> 
>> I have this simple pig script but when I run I get:
>> 
>> 2012-08-28 17:50:24,924 [main] INFO
>> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
>> - Failed!
>> 2012-08-28 17:50:24,939 [main] ERROR org.apache.pig.tools.grunt.Grunt -
>> ERROR 1066: Unable to open iterator for alias C
>> 
>> DEFINE SequenceFileLoader
>> org.apache.pig.piggybank.storage.SequenceFileLoader();
>> A = LOAD '/flume_vol/flume/2012/08/24/13/dslg1/*.snappy' USING
>> SequenceFileLoader AS (key:long, document:bytearray);
>> B = GROUP A BY key;
>> C = foreach B generate COUNT(A);
>> dump C;
>> 
>> 
>> I do see data in the files:
>> 
>> hadoop fs -cat
>> /flume_vol/flume/2012/08/24/13/dslg1/web.1345840674870.snappy|more
>> SEQ!org.apache.hadoop.io.LongWritable"org.apache.hadoop.io.BytesWritable)org.apache.hadoop.io.compress.SnappyCodec
>> ~

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