[PIG-2312] NPE when relation and column share the same name and used in Nested Foreach

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.9.0
• Release Note: Unlinking from 0.11 for the same reason
• Assignee: Vivek Padmanabhan
• Reporter: Vivek Padmanabhan
• Created: 30/Sep/11 12:41
• Updated: 25/Jan/13 19:14

Description

With Pig0.9, if a relation and a column has the same name and if the column is used in a nested foreach, the script execution fails
while compiling.
The below is the trace;

java.lang.NullPointerException
	at org.apache.pig.newplan.logical.visitor.ScalarVisitor$1.visit(ScalarVisitor.java:63)
	at org.apache.pig.newplan.logical.expression.ScalarExpression.accept(ScalarExpression.java:109)
	at org.apache.pig.newplan.DependencyOrderWalker.walk(DependencyOrderWalker.java:75)
	at org.apache.pig.newplan.PlanVisitor.visit(PlanVisitor.java:50)
	at org.apache.pig.newplan.logical.optimizer.AllExpressionVisitor.visit(AllExpressionVisitor.java:142)
	at org.apache.pig.newplan.logical.relational.LOSort.accept(LOSort.java:119)
	at org.apache.pig.newplan.DependencyOrderWalker.walk(DependencyOrderWalker.java:75)
	at org.apache.pig.newplan.logical.optimizer.AllExpressionVisitor.visit(AllExpressionVisitor.java:104)
	at org.apache.pig.newplan.logical.relational.LOForEach.accept(LOForEach.java:74)
	at org.apache.pig.newplan.DependencyOrderWalker.walk(DependencyOrderWalker.java:75)
	at org.apache.pig.newplan.PlanVisitor.visit(PlanVisitor.java:50)
	at org.apache.pig.PigServer$Graph.compile(PigServer.java:1674)
	at org.apache.pig.PigServer$Graph.compile(PigServer.java:1666)
	at org.apache.pig.PigServer$Graph.access$200(PigServer.java:1391)
	at org.apache.pig.PigServer.execute(PigServer.java:1293)
	at org.apache.pig.PigServer.executeBatch(PigServer.java:359)
	at org.apache.pig.tools.grunt.GruntParser.executeBatch(GruntParser.java:131)
	at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:192)
	at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:164)
	at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:81)
	at org.apache.pig.Main.run(Main.java:553)
	at org.apache.pig.Main.main(Main.java:108)

This could be reproduced with the below script

f3 = load 'input.txt' as (a1:chararray);
A = load '3char_1long_tab' as (f1:chararray, f2:chararray, f3:chararray,ct:long);

B = GROUP A  BY f1;
C =    FOREACH B {
        zip_ordered = ORDER A BY f3 ASC; 
        GENERATE
                FLATTEN(group) AS f1,	
                A.(f3, ct),
		COUNT(zip_ordered),
                SUM(A.ct) AS total;
  };

STORE C INTO 'deletemeanytimeplease';

Checked with a unit test in trunk, the behavior is still same.