Oracle developer:
Has basic understanding of data model Can write SQL code to manipulate and query data efficiently.
Also understands query execution plans.
Can write shell scripts
Knowing Python language is a bonus
Experience with 2. SQL tuner
Understands Oracle database architecture very well
Understands Exadata capabilities at high level
Understands how to read and interpret SQL execution plans and knows how to identify bottlenecks and tune the SQL or the database to improve and get maximum performance out of Oracle database
Can read AWR, SQL monitor report, interpret, explain required changes, implement the changes and demonstrate performance improvement after improvement.