TO PRIMARY This standby database can switch over to a primary database.
TO STANDBY This primary database can switch over to a standby database.
TABLE 13-2 SWITCHOVER_STATUS Values
Chapter 13: Oracle Data Guard 489
If you add the with session shutdown wait clause, the statement will not return to the SQL>
prompt until the switchover is complete. Start up the database using the open keyword:
alter database open;
The database has completed its transition to the primary database role. Next, start the redo
apply services on the standby databases if they were not already running in the background:
alter database recover managed standby database using current logfile
disconnect from session;
Switchovers to Logical Standby Databases
Switchovers are initiated on the primary database and completed on the standby database. In this
section, you will see the steps for performing a switchover to a logical standby database.
Begin by verifying that the primary database is capable of performing a switchover. Query
V$DATABASE for the value of the Switchover_Status column:
select switchover_status from v$database;
For the switchover to complete, the status must be either TO STANDBY, TO LOGICAL STANDBY,
or SESSIONS ACTIVE.
In the primary database, issue the following command to prepare the primary database for the
switchover:
alter database prepare to switchover to logical standby;
In the logical standby database, issue the following command:
alter database prepare to switchover to primary;
At this point, the logical standby database will begin transmitting its redo data to the current
primary database and to the other standby databases in the configuration.
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