But this only guarantees that the results will be sorted within each reducers input. Thus, this won't result in getting the results sorted by the reducers output value.
On 2/21/08 8:40 PM, "Owen O'Malley" <[EMAIL PROTECTED]> wrote: > > On Feb 21, 2008, at 5:47 PM, Ted Dunning wrote: > >> It may be sorted within the output for a single reducer and, >> indeed, you can >> even guarantee that it is sorted but *only* by the reduce key. The >> order >> that values appear will not be deterministic. > > Actually, there is a better answer for this. If you put both the > primary and secondary key into the key, you can use > JobConf.setOutputValueGroupingComparator to set a comparator that > only compares the primary key. Reduce will be called once per a > primary key, but all of the values will be sorted by the secondary key. > > See http://tinyurl.com/32gld4 > > -- Owen
