Hi Jackob,A combiner acts a lot like a reduce step but it's executed on the mapper with in-memory data. I've seen a reduction in job execution time by adding one. The one caveat to keep in mind is that it may or may not run on a particular map attempt.
Nick On 8/2/2010 10:39 AM, Jackob Carlsson wrote:
Hi everyone, Could anyone please help me to understand the function of combiner? Thanks in advance Jackob
