On Fri, 16 Sep 2011 08:26:35 -0500, harry lippy <harryli...@gmail.com> wrote: > The keys are file offsets into the input file. My question: how did the > 'are presented to the map function as key-value pairs' happen? I've run > the > example on the input file using the java Mapper, Reducer, and the code that > runs the job - none of which seems, to my novice eye, to massage the input > from the file to the map function in the (file offset, line of data from > file) key-value format - and the results are correct.
There are actually MANY classes in the framework floating around, most of which you Don't Need to Know About on a day-to-day basis. One of them is called an InputFormat, which handles getting input and parsing it into records. These classes can all be replaced with appropriate configurations, but the defaults are usually pretty good for most purposes.
