Please disregard this question. I think I'm mistaken. On Sat, Jun 27, 2009 at 10:25 AM, Stuart White <stuart.whi...@gmail.com>wrote:
> If I call HashPartitioner.getPartition(), passing a key of 4 and a > numPartitions of 5, it returns a partition of 4. (Which is what I would > expect.) > > However, if I have a mapred job, and in my mapper I emit a record with key > 4, I'm configured to use the HashPartitioner, I have 5 Reducers configured, > and I'm using the IdentityReducer, the record with key 4 gets handled by > Reducer #0 (because it gets written out to part-00000). > > I would have expected a record with key 4 to be handled by reducer #4 (and > therefore written to part-00004) because the HashPartitioner returns 4 for a > key of 4 and a numPartitions of 5. > > Obviously I'm missing something here. What is the logic for deciding which > partition of records is handled by which reducer instance? > > It can't be random, otherwise mapside join wouldn't work. > > Thanks. >
