Oracle DBA Pocket Guide

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Oracle DBA Pocket Guide

WARNING

Although the SPFILE looks like a plain text file, it is very

important to realize that the SPFILE must not be edited

directly. If you edit your SPFILE (with a text editor, for ex-

ample), then the next attempt to start your database will

result in a failure. You will be unable to start your data-

base unless you have created a backup INIT.ORA file

(which is a good practice for just this reason).

Dynamic and Static Parameters

While most initialization parameters are static, taking their

values from the initialization file as it exists at the time of

database startup, some may be dynamically modified while

the instance is up and the database is open.

Dynamic modification is different from dynamic storage of a

changed value in the SPFILE. In all versions of Oracle, you

can dynamically modify a setting using the ALTER SYSTEM

or ALTER SESSION command. These changes may also be

dynamically stored in the SPFILE, depending on the value of

the SCOPE clause of the ALTER command.

NOTE

Remember that if you use an INIT.ORA file, dynamic

changes to parameters will never be saved to it; you must

edit the INIT.ORA file yourself (or recreate it from the

SPFILE).

Backup and Recovery

Even with redundant hardware, you will still need to back up

your database. You can do this through a logical backup

(export) or a physical backup at the datafile level. As you’d

expect, there are trade-offs