A
Restrictions

This appendix documents Real Application Clusters compatibility issues and restrictions. Topics in this appendix include:

• Compatibility
• Restricted SQL Statements
• Maximum Number of Datafiles

Compatibility

Real Application Clusters runs with any Oracle database created in exclusive (X) mode. Oracle in exclusive mode can access a database created or modified by the Real Application Clusters software. In addition, each instance must have its own set of redo logs.

Restricted SQL Statements

In cluster database mode, the following operations are not supported:

• Creating a database (CREATE DATABASE)
• Creating a control file (CREATE CONTROLFILE)
• Switching the database's archiving mode (the ARCHIVELOG and NOARCHIVELOG options of ALTER DATABASE)

To perform these operations, shut down all instances and start up one instance in exclusive mode.

Maximum Number of Datafiles

The number of datafiles supported by Oracle is operating system-specific. Within this limit, the maximum number allowed depends on the values used in the CREATE DATABASE command. This in turn is limited by the physical size of the control file. This limit is the same in cluster database mode as in exclusive mode, but the additional instances of Real Application Clusters restrict the maximum number of files more than a single instance system.