Cache in TimesTen Works With Synchronous Data Guard
Cache in TimesTen works with synchronous physical standby failover and switchover and logical standby switchover as long as the object IDs for cached Oracle Database tables remain the same on the primary and standby Oracle databases.
Object IDs can change if the table is dropped and re-created, altered, or a truncated flashback operation or online segment shrink is performed.
During a transient upgrade, a physical standby Oracle database is transformed into a logical standby Oracle database. For the time that the standby Oracle database is logical, the user must ensure that the object IDs of the cached Oracle Database tables do not change. Specifically, tables that are cached should not be dropped and re-created, truncated, altered, flashed back or have an online segment shrunk.
The following sections describe how to configure the Oracle and TimesTen databases.
Configuring the Oracle Databases for TimesTen and Synchronous Data Guard
You can configure TimesTen to fail over and switch over when using synchronous Data Guard.
In order for TimesTen to fail over and switch over properly, configure the primary and standby Oracle databases using the following steps:
Before performing a switchover to a logical standby database, stop the Oracle Database service for TimesTen on the primary database and disconnect all sessions connected to that service. Then start the service on the standby database.
At this point, cache applications try to reconnect to the standby database. If a switchover occurs, there is no wait required to migrate the connections from the primary database to the standby database. This eliminates the performance impact on TimesTen and its applications.