Monday, October 17, 2005

Oracle Database 10g Release 2: Online Limit Changes

This feature is pretty useful as we don't have to re-create the controlfile to make the changes any more. Previously, taking such an action is critical and dangerous. You must be very careful to rebuild the controlfile. Moreover, the database must be opened in RESETLOG mode and a lot of information will be lost during the process.

Oracle Database 10g Release 2: Top Features for DBAs: "Online Limit Changes

When you want change parameters defined during the creation of the database, such as MAXDATAFILES, MAXLOGFILES, and so on, what are your options? Prior to Oracle Database 10g Release 2, the only option is to follow these steps:

1. Take a backup of controlfile to trace.
2. Modify the parameter you want to change in that trace file.
3. Shut the database down.
4. Startup Mount.
5. Recreate the control file.
6. Open the database in RESETLOGS mode.

Needless to say, this approach degrades availability. In addition, because RMAN keeps the metadata about backups in the control file as well as in the catalog, that information is lost during this process. The controlfile is created in RESETLOGS mode, so some backup information may be lost too.

In Oracle Database 10g Release 2, you needn't recreate the control file to change these parameters. Thus, you do not have to lose the RMAN information stored there."

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