If you have huge data file(s), you may want to look at datastore.
First datastore can apply on fileS, folder.
Then if you don't specify it, datastore wit not deal file by file but block by block and will simply treat another file when the current one is finish.
For column data, you can specify which column to really import (very effective if you know you only wants some of the columns and not everyone).
Is your files have the same number of column and they contains the same "data" (I mean for instance column 1 in your two file represent the ssame observation like Name, age, height, ....)?