Something to keep in mind though, sorting is appropriate to the key type. Text will be sorted lexicographically.
Nick Jones ----- Original Message ----- From: Ed Mazur <ma...@cs.umass.edu> To: common-user@hadoop.apache.org <common-user@hadoop.apache.org> Sent: Tue Mar 30 21:07:29 2010 Subject: Re: question on shuffle and sort On Tue, Mar 30, 2010 at 9:56 PM, Cui tony wrote: > Did all key-value pairs of the map output, which have the same key, will > be sent to the same reducer tasknode? Yes, this is at the core of the MapReduce model. There is one call to the user reduce function per unique map output key. This grouping is achieved by sorting which means you see keys in increasing order. Ed
