The configuration file, usually referred to as the CONFIG.ORA file, is an optional file that contains parameters, just like the INIT.ORA file. In fact, the CONFIG.ORA file is a subset of the INIT.ORA file, and can only be used if the INIT.ORA file contains an “include” line specifying the name of the CONFIG.ORA file. Since the CONFIG.ORA file is actually merged into the INIT.ORA file prior to processing by Oracle, all of the same syntax rules apply.

The CONFIG.ORA file is primarily used to segregate a particular set of standard initialization parameters. For example, when running the Oracle Parallel Server, there are many initialization parameters that must be set identically for each instance, and these are stored in a separate CONFIG.ORA file. Similarly, several Oracle instances running on the same host may share a common subset of parameters that is stored in a single CONFIG.ORA file, while each instance also has a set of specific initialization parameters stored in its INIT.ORA file.