switching patches on and off

You want to play around with optimizer-patches in your DB?

you want to break your DB a curious way?

have a look at v$system_fix_control and v$session_fix_control and gamble by change the parameter _fix_control. I also found  _fix_control_key but no information about it.

For more than one patch to switch, use 
alter session set "_fix_control"='4728348:OFF','4663698:OFF'; i learned here.

What is it good for?

To test if the just-applied patch works as expected.

Recommended? 

Patches are to fix bugs. Playing around with bugs is a job for exterminators.

Happy playing ;-)