ERROR 1066: Unable to open iterator for alias in pig - user-defined-functions

Question

I am running a pig script which is as follows
REGISTER '/home/vishal/FirstUdf.jar';
DEFINE UPPER com.first.UPPER();
A = LOAD '/home/vishal/exampleforPIG1' AS (exchange: chararray, symbol: chararray, date: int,value:float);
B= FOREACH A GENERATE com.first.UPPER(exchange);
DUMP B;
Following is my UDF in java
package com.first;
import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.util.WrappedIOException;
#SuppressWarnings("deprecation")
public class UPPER extends EvalFunc<String> {
public String exec(Tuple input) throws IOException {
if (input == null || input.size() == 0)
return null;
try {
String str = (String) input.get(0);
return str.toLowerCase();
} catch (Exception e) {
throw WrappedIOException.wrap(
"Caught exception processing input row ", e);
}
}
}
Now when i try to run that ,it gives me the following error
Pig Stack Trace
ERROR 1066: Unable to open iterator for alias B
org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1066: Unable to open iterator for alias B
at org.apache.pig.PigServer.openIterator(PigServer.java:866)
at org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:683)
at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:303)
at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:190)
at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:166)
at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:84)
at org.apache.pig.Main.run(Main.java:430)
at org.apache.pig.Main.main(Main.java:111)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:156) Caused by: java.io.IOException: Job terminated with anomalous status FAILED
at org.apache.pig.PigServer.openIterator(PigServer.java:858)
... 12 more
Whys is that in pig script it is not able to open an iterator for B ie (it is not able to assign an iterator for the following line)
B = FOREACH A GENERATE com.first.UPPER(exchange);
'exampleforPIG1' file has following data
NYSE CPO 2009-12-30 0.14
NYSE CPO 2009-09-28 0.14
NYSE CPO 2009-06-26 0.14
NYSE CPO 2009-03-27 0.14
NYSE CPO 2009-01-06 0.14
NYSE CCS 2009-10-28 0.414
NYSE CCS 2009-07-29 0.414
..
..
etc

Answer 1

Well two things,
If all you want to do is typecast to upper/lower case, why not use the inbuilt functions UPPER/LOWER.
You can find the usage in the reference manuals.
If you want to continue in the same method,
it should be
B = FOREACH A GENERATE UPPER(exchange);
You have already defined it as DEFINE UPPER com.first.UPPER();

Answer 2

I faced this issue and after breaking my head I found that the flaw was in the input data, even though I was cleaning by replacing null. I had a single record which had fields like '(null)', and it was causing everything to fail. Just check this once, if you have bad records like this.

Answer 3

Its the avro version which caused this error for me.
I was using avro-1.7.6.jar. Changing it to avro-1.4.0.jar solved my issue.

Answer 4

Are you running a pig 0.12.0 or earlier jar against hadoop 2.2, if this is the case then I managed to get around this error by recompiling the pig jar from src, here is a summary of the steps involved on a debian type box
download the pig-0.12.0.tar.gz
unpack the jar and set permissions
then inside the unpacked directory compile the src with 'ant clean jar -Dhadoopversion=23'
then you need to get the jar on your class-path in maven, for example, in the same directory
mvn install:install-file -Dfile=pig.jar -DgroupId={set a groupId}-
DartifactId={set a artifactId} -Dversion=1.0 -Dpackaging=jar
or if in eclipse then add jar as external libary/dependency
I was getting your exact trace trying to run pig 12 in a hadoop 2.2.0 and the above steps worked for me
UPDATE
I posted my issue on the pig jira and they responded. They have a pig jar already compiled for hadoop2 pig-h2.jar here http://search.maven.org/#artifactdetails|org.apache.pig|pig|0.12.0|jar
a maven tag for this jar is
org.apache.pig
pig
h2
0.12.0
provided

Answer 5

Safe mode is also on of reason for this exception
run the below command
hadoop dfsadmin -safemode leave