I'm working with python 3.6 on ubuntu 16.04 and trying to connect with Oracle database which is installed in another machine. So i have installed "cx_Oracle" python module by following this link. Now, my doubt is what is the necessity to install oracle client in my machine when i need to access the database from another machine in my python script?
The Oracle Client libraries provide all the necessary network connectivity (e.g. things like network encryption), connection management (e.g. connection pooling), high availability features, cross platform and Oracle-version support, data caching, etc etc etc. They are used by many different user and applications. They have significant engineering in them, not to mention testing.
cx_Oracle makes calls to the Oracle Client libraries (which are freely available in Oracle Instant Client), so you need those libraries.