Why are PL/SQL ref cursors important to PL/SQL performance?

The ref cursor is a "pointer" data types that allows you to quickly reference any cursor result (usually an internal PL/SQL table array) with data values kept in super-fast RAM.

I'm a big fan of Dr. Hall, one of the world's top PL/SQL programming guru's, and I'm referencing his wonderful book "PL/SQL Tuning" where he has many ref cursor examples and ref cursor tips.

Definition of a ref cursor

The name "ref cursor" can be confusing because a ref cursor variable is not a cursor, but a variable that points to a cursor.  In essence, a ref cursor allows you to store the result of a "bulk collect" from a table (or any PL/SQL cursor return set) into a PL/SQL table (RAM array) and then reference the array with the ref cursor as a pointer.  Here is a simple example of using a ref cursor.

Once you load a PL/SQL table (an in-RAM array), a ref cursor allows you to reference the array within your PL/SQL code without having to pass the array to a new procedure or function.  Instead of passing the "baggage" of the actual RAM array, you simple pass the ref cursor, which points to the array values.