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
~

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
> ~

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
>> ~