(1)switchover:
主库:alter database prepare to switchover to logical standby;
备库:alter database prepare to switchover to primary;
--此时,备库应该将日志应用完毕
alter database start logical standby apply:
主库:alter database commit to switchover to logical standby;
备库:alter database commit to switchover to primary;
上原来的主库查询:
select database_role from v$database;
DATABASE_ROLE
----------------
LOGICAL STANDBY
然后上备库查:
select database_role from v$database;
DATABASE_ROLE
----------------
PRIMARY
(2)failover:
如果主库发生故障,要将备库作为主库,运行:
alter database activate logical standby database;
startup force;
备库起来以后,变成了主库。