[PIG-2530] Reusing alias name in nested foreach causes incorrect results

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 0.9.2, 0.10.0
• Fix Version/s: 0.10.0, 0.9.3, 0.11
• Hadoop Flags: Reviewed
• Assignee: Daniel Dai
• Reporter: Vivek Padmanabhan
• Created: 13/Feb/12 09:48
• Updated: 01/Aug/13 19:30
• Resolved: 16/Feb/12 20:13

Description

The below script results in incorrect output for Pig 0.10 but runs fine with Pig 0.8,

input.txt
1	4
1	3
2	3
2	4

a = load 'input.txt' as (v1:int, v2:int);
b = group a by v1;
c = foreach b { x = a; x = order x by v2 asc; generate flatten(x); }
store c into 'c1';

Output from Pig 0.10
--------------------
1 4
1 3
2 3
2 4

Looking at the explain, it seems like the sorting is entirely missed out.
The script produces correct results if I change the alias name ie;

c = foreach b

{ x = a; x1 = order x by v2 asc; generate flatten(x1); }