RE: what is the difference between spfile and pfile?
An spfile and a pfile are both init parameter files.
The pfile is a readable text file which you can edit directly in Notepad (Windows) or vi (Unix). The pfile's name is initSID.ora.
The spfile is a binary file which means it can't be edited directly (if you try to edit it directly it'll corrupt the file). The spfile can only be modified by using the "alter system" command. The spfile's name is spfileSID.ora.
The spfile is useful to have because it lets you dynamically make changes to some parameters whereas the pfile does not - you will need to shutdown and startup the instance for any changes you make in the pfile to be applied.
