Mark Wagner created PIG-3568:
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Summary: Define the semantics of POStatus.STATUS_NULL
Key: PIG-3568
URL: https://issues.apache.org/jira/browse/PIG-3568
Project: Pig
Issue Type: Bug
Reporter: Mark Wagner
Assignee: Mark Wagner
The meaning of POStatus.STATUS_NULL is not well documented and there are
conflicting view points on its interpretation. The two interpretations are:
1. POStatus.STATUS_NULL indicates that the pulled output IS null. This is
mostly found in expression operators, particularly comparison operators.
2. POStatus.STATUS_NULL indicates that the pull did not produce any output.
This is backed up by its usage in POPackage (not JoinPackage) for flattening an
empty bag, and PigGenericMapBase where pulls on the operator pipeline that
result in STATUS_NULL are discarded.
I propose that 2 should be the official definition going forward. The first
meaning is easily indicated by (null, STATUS_OK) and all the relational
operators already seem to follow 2. I'd like others opinions as well though.
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