[Hadoop-common-dev] Why part files are not merged ?

Hi all,

Each reduce task produces one part file in the DFS. Why the job tracker
does not merge them at the end of the job to produce only one file.
It seems to me that it could be better to process results.

I think there is certainly a reason for the actual behavior but I really
need to get results of my map reduce job in a single file. Maybe someone
can give me a clue to solve my problem.

Thanks for any help.

Thomas.