[PIG-2659] add source location of the aliases in the physical plan

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.11
• Component/s: impl
• Patch Info: Patch Available
• Assignee: Julien Le Dem
• Reporter: Julien Le Dem
• Created: 23/Apr/12 22:07
• Updated: 22/Feb/13 04:53
• Resolved: 12/May/12 15:00

Description

The goal is to provide better information about what is actually running in a job.
In particular when alias names are being reused.

For example with the following script:

A = LOAD 'foo' using PigStorage();
B = GROUP A BY $0;
A = FOREACH B GENERATE COUNT(A);
STORE A INTO 'bar';

The job conf will contain the following information

pig.alias.location: M: A[1,4],A[3,4],B[2,4] C: A[3,4],B[2,4] R: A[3,4]

A caveat is that the Logical Plan Optimizer throws away the original information when merging Logical Operators.
this is already the case today with pig.alias