pig.maxCombinedSplitSize not work

I have an input directory which has 7 files:
804M bid10.gz
814M bid11.gz
808M bid2.gz
812M bid4.gz
803M bid5.gz
818M bid8.gz
823M bid9.gz

In my pig script i set combined size to 128M

SET pig.maxCombinedSplitSize 134217728;

But there's only 7 mapper.(one file per mapper)
Any insight on this?

Thanks,
Lei

leiwangouc [ at ] gmail.com