Oracle 12c Release 2 has 412 different documented and 4237 different undocumented initialization (
spfile.ora) parameters. This means you have a total of 4649 initialization parameters to play with; you can do a
count(*) of X$KSPPI for the total number of parameters both documented and undocumented (you need to be SYS to access the X$ tables). A count of V$PARAMETER gives you a count of only the documented parameters. When I refer to the undocumented parameters, I am referring to parameters that start with an underscore (_), although some of them are actually even documented. There are also ...