Question: What is an Oracle ifile,
and how is the ifile used within Oracle parameter files?
Answer:
The Oracle ifile ("include file")
was introduced as a way to include a smaller parameter file
within another Oracle parameter file. For example, we
can embed a common listener.ora parameter file inside a
regular listener.ora file by adding the embedded code.
In this ifile example, we include a file in /tmp called
listener_master.ora:
IFILE=/tmp/listener_master.ora
Oracle supports up to three levels of ifile nesting
allowing you to have an ifile within an ifile, within an
ifile.
The ifile is most commonly used in large environments
when you want to include one tnsnames.ora file within many
other tnsnames.ora files.
According to some Oracle experts, the ifile facility was
designed for the init.ora file and ifile is not supported
for the listener.ora, sqlnet.ora and protocol.ora files, but
Oracle eBusiness Suite (EBS) release 11 uses ifile in their
parameter files, ostensibly for reasons of customizations.
With a ifile, you can leave the original file intact and not
wonder what was added later.
Further, there is little mention of the ifile facility on
the Oracle documentation, but it does appear on the Oracle
10g release 2 documentation.
Personally, I do not use ifile, since most environments
are static enough that the ifile is not worth the trouble.
