The Oracle SPFILE

The SPFILE is different from the PFILE in that it can not be directly edited. This is because it has a header and footer that contains binary values. Since you can not change a SPFILE directly, Oracle allows you to manage the SPFILE via the alter system command.

That might sound a bit more complex, but it really is no harder than manually changing a PFILE. For using an SPFILE, you can reap great benefits. It can be backed up by RMAN every time a change is made or when the database is backed up, which means it is easier to recover. Also, SPFILES allow you to make dynamic changes to parameters that are persistent. For example, remember that we said this database parameter change was not persistent if we were using PFILES:

Alter system set db_recovery_file_dest_size=10g;

If we were using SPFILES the parameter would keep the same value, even after a database restart. This means you only have to change the parameter value in one place, and that you can forget having to change it in the PFILE of the database.

One of the most important benefits of the SPFILE is that Oracle has introduced many automatic tuning features into the core of the database. Without an SPFILE, Oracle can not autotune your database.

An SPFILE uses the same formatting for its file name as the PFILE, except the word spfile replaces init. For instance, if your ORACLE_SID is testdb, the resulting spfile would be called spfiletestdb.ora.