Hive Tez on External Table running on Single Mapper

[Mahender Sarangam]

Hi,

We have 20 GB txt File, When we have created external table on top of 20 
Gb file, we see Tez is creating only one mapper. We have applied setting 
like reducing distribution block size less 128 MB. Manually Set Mappers 
and Reducer but of no use. We are using Tez 0.7 version, is there any 
setting which makes application to run in more than one mapper. Input 
file is not Compressed, it's a Txt File with 100 columns.