Understanding Flashback Technology - OCP: Oracle Database 12c Administrator Certified Professional - page 365

Disabling and Enabling the Recycle Bin
It is important to understand that even though the Recycle Bin is extremely useful, its use
is entirely optional. Though it is enabled by default, it can be turned off at either the system
or session level to suit the users' needs. For instance, if you work in an environment that is
very tight on space, the Recycle Bin might be more of a hindrance than a help.
The Recycle Bin feature is governed by an initialization parameter named RECYCLEBIN .
As with other initialization parameters, it can be set in the INIT.ORA file as shown:
RECYCLEBIN=OFF
For a database using spfiles, the same thing can be accomplished, as shown here:
SQL> alter system set recyclebin = off scope=spfile;
System altered.
You can't dynamically enable or disable the Recycle Bin at a system level for existing
sessions, but you can for future sessions:
SQL> show parameter recyclebin
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
recyclebin string on
SQL> alter system set recyclebin=off;
alter system set recyclebin=off
*
ERROR at line 1:
ORA-02096: specified initialization parameter is not modifiable with this
option
SQL>
SQL> alter system set recyclebin = off DEFERRED;
System altered.
Enabling the Recycle Bin can also occur at the session level, as shown in the following
example:
SQL> alter session set recyclebin = off;
Session altered.