Hi, Does every block of files in HDFS have to be the same file format when writing map-reduce applications, a more specific question is , when dealing with CSV files, can we have a head in the file? I have seen Mahout applications using the UCI repository file format which is similar as CSV without header, does it because all map reduce task must run semantically, having a header will cause one map task be unique to others.
Regards, Xiaobo Gu
