[PIG-563] PERFORMANCE: enable combiner to be called 0 or more times whenver the combiner is used for a pig query

• Type: Improvement
• 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: 13/Dec/08 01:42
• Updated: 24/Mar/10 22:04
• Resolved: 24/Dec/08 00:48

Description

Currently Pig's use of the combiner assumes the combiner is called exactly once in Hadoop. With Hadoop 18, the combiner could be called 0, 1 or more times. This issue is to track changes needed in the CombinerOptimizer visitor and the builtin Algebraic UDFS (SUM, COUNT, MIN, MAX, AVG) to be able to work in this new model.