I'm asking about Oracle, but I'm also learning hbase, so I'm a little confused. I'm not a database guy; I'm a java guy who is now into Hadoop and hasn't touched a database in over a year. There are other reasons for this, but we will not go into them. I am very aware of what I am doing. I'm a newbie MR coder, but I'm doing okay with my part of the code.
I have a table with ten columns and would want to choose column 1
and column 9 from it. How many columns should be selected
internally in RDBMS? Also, I'm not an expert in 3-Level
Architecture of DBMS to understand [data
independence](https://www.scaler.com/topics/data-independence-in-dbms/) but I've read several resources.
