i have a simple map-reduce job that i test with only 2 mappers, 2 reducers and very small input (10 lines of text).
it runs fine without compression. but as soon as i turn on compression (mapred.compress.map.output=true), the output files (part-00000.snappy, etc.) are empty. zero records. using logging i can see that my reducer succesfully calls output.collect(key, value) yet they dont show up in the file. i tried both snappy and gzip. do i need to do some sort of flushing? i am on hadoop 0.20.2
