Pfile Vs Spfile
PFILE :
PFILE is a text file which can be modified by text editor. Oracle server required PFILE to start an oracle Instance.
SPFILE :
SPFILE is a binary file which can not be modified by text editor. It is created from PFILE.
When the Oracle instance start, first it looks to the $ORACLE_HOME/dbs (UNIX, Linux) or ORACLE_HOME/database (Windows) directory for the following files (in this order):
1. spfileSID.ora (SPFILE)
2. Default SPFILE (SPFILE)
3. initSID.ora (PFILE)
4. Default PFILE (PFILE)
SPFILE advantages
1. No need to restart the database in order to have a parameter changed and the new value stored in the initialization file
2. Reduce human errors: Parameters are checked before changes are accepted
3. An SPFILE can be backed-up with RMAN (RMAN cannot backup PFILEs)
How could I switch from SPFILE to PFILE and vice-versa?
Switch from SPFILE to PFILE:
1) CREATE PFILE FROM SPFILE;
2) Backup and delete SPFILE
3) Restart the instance
Switch from PFILE to SPFILE:
1) CREATE SPFILE FROM PFILE=’Location of the PFILE’;
2) Restart the instance (the PFILE will be in the same directory but will not be used. SPFILE will be used instead)
This could be done in order to have a backup in the other format or to change the initialization file for the database instance.
CREATE PFILE FROM SPFILE;
CREATE SPFILE FROM PFILE='/oradata/initORCL.ora';
CREATE SPFILE = '/oradata/spfileORCL.ora' FROM PFILE = '/oradata/initORCL.ora' ;
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