question

[Orieta Celiku]

Hi,

I'm trying to follow a few simple steps in the Pig tutorial. I'm running Pig 
locally.

Starting with myfile.txt as

1       2       3
4       2       1
8       3       4
4       3       3
7       2       5
8       4       3

and doing the following steps

A = LOAD 'examples/myfile.txt' USING PigStorage('\t') AS (f1,f2,f3);
dump A;
Y = FILTER A BY (f1 == '8');
dump Y;
X = FILTER A BY (f1 == '8') OR (NOT (f2+f3 > f1));
dump X;
X2 = FOREACH A GENERATE (f1+f2) as f1f2;
dump X2;

so far all goes well. I then try
X3 = FILTER X2 BY f1f2 > '5'; 
dump X3; 

and I get the exceptions below. What's worse at this point if I try to dump X2, 
similar exceptions are raised.

Can someone point out to what the problem might be? 

Thanks, 
Orieta



2008-04-21 15:14:48,659 [main] ERROR org.apache.pig.tools.grunt.GruntParser - 
java.io.IOException: Unable to open iterator for alias: X3
        at 
org.apache.pig.impl.util.WrappedIOException.wrap(WrappedIOException.java:16)
        at org.apache.pig.PigServer.openIterator(PigServer.java:330)
        at 
org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:254)
        at 
org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:160)
        at 
org.apache.pig.tools.grunt.GruntParser.parseContOnError(GruntParser.java:72)
        at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:54)
        at org.apache.pig.Main.main(Main.java:253)
Caused by: org.apache.pig.backend.executionengine.ExecException: 
java.lang.NullPointerException
        at 
org.apache.pig.backend.local.executionengine.LocalExecutionEngine.execute(LocalExecutionEngine.java:137)
        at 
org.apache.pig.backend.local.executionengine.LocalExecutionEngine.execute(LocalExecutionEngine.java:32)
        at org.apache.pig.PigServer.optimizeAndRunQuery(PigServer.java:400)
        at org.apache.pig.PigServer.openIterator(PigServer.java:319)
        ... 5 more
Caused by: java.lang.NullPointerException
        at org.apache.pig.impl.eval.GenerateSpec$1.add(GenerateSpec.java:86)
        at org.apache.pig.impl.eval.EvalSpec.simpleEval(EvalSpec.java:223)
        at org.apache.pig.impl.eval.FuncEvalSpec$1.add(FuncEvalSpec.java:108)
        at 
org.apache.pig.impl.eval.GenerateSpec$CrossProductItem.exec(GenerateSpec.java:263)
        at org.apache.pig.impl.eval.GenerateSpec$1.add(GenerateSpec.java:88)
        at 
org.apache.pig.backend.local.executionengine.POEval.getNext(POEval.java:100)
        at 
org.apache.pig.backend.local.executionengine.POEval.getNext(POEval.java:94)
        at 
org.apache.pig.backend.local.executionengine.LocalExecutionEngine.execute(LocalExecutionEngine.java:130)
        ... 8 more