Online Upgrade: Using TimesTen Replication

When upgrading to a new release of TimesTen Classic, you may have a mission-critical database that must remain continuously available to your applications. You can use TimesTen replication to keep two copies of a database synchronized, even when the databases are from different releases of TimesTen, allowing your applications to stay connected to one copy of the database while the instance for the other database is being upgraded. When the upgrade is finished, any updates that have been made on the active database are transmitted immediately to the database in the upgraded instance, and your applications can then be switched with no data loss and no downtime. See "Performing an Online Upgrade with Classic Replication" for information.

The online upgrade process supports only updates to user tables during the upgrade. The tables to be replicated must have a PRIMARY KEY or a unique index on non-nullable columns. Data definition changes such as CREATE TABLE or CREATE INDEX are not replicated except in the case for an active standby pair with DDLReplicationLevel set to 2. In the latter case, CREATE TABLE and CREATE INDEX are replicated.

Because two copies of the database (or two copies of each database, if there are more than one) are required during the upgrade, you must have available twice the memory and disk space normally required, if performing the upgrade on a single host.

Note:

• Online major upgrades for active standby pairs with cache groups are only supported for read-only cache groups.

• Online major upgrades for active standby pairs that are managed by Oracle Clusterware are not supported.