[PIG-634] When POUnion is one of the roots of a map plan, POUnion.getNext() gives a null pointer exception

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.2.0
• Fix Version/s: 0.2.0
• Assignee: Pradeep Kamath
• Reporter: Pradeep Kamath
• Created: 24/Jan/09 01:16
• Updated: 24/Mar/10 22:04
• Resolved: 26/Jan/09 21:29

Description

POUnion.getnext() gives a null pointer exception in the following scenario (pasted from a code comment explaining the fix for this issue). If a script results in a plan like the one below, currently POUnion.getNext() gives a null pointer exception

                
                // POUnion
                // |
                // |--POLocalRearrange
                // |    |
                // |    |-POUnion (root 2)--> This union's getNext() can lead the code here
                // |
                // |--POLocalRearrange (root 1)
                
                // The inner POUnion above is a root in the plan which has 2 roots.
                // So these 2 roots would have input coming from different input
                // sources (dfs files). So certain maps would be working on input only
                // meant for "root 1" above and some maps would work on input
                // meant only for "root 2". In the former case, "root 2" would
                // neither get input attached to it nor does it have predecessors

A script which can cause a plan like above is:

a = load 'xyz'; 
b = load 'abc'; 
c = union a,b; 
d = load 'def'; 
e = cogroup c by $0 inner , d by $0 inner;
dump e;