alter database recover managed standby database disconnect from session; 開啓同步重做日誌，（使用歸檔日誌進行同步）管理模式
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION; 開啓同步重做日誌，使用在線日誌進行同步）管理模式
alter database recover managed standby database cancel; 管理模式到只讀模式
select process,status from v$managed_standby; 查看日誌應用
SELECT PROCESS, STATUS, THREAD#, SEQUENCE#,BLOCK#,BLOCKS,PID FROM V$MANAGED_STANDBY; 查看日誌詳細應用，進程工作狀態
alter database open read only; 開啓到只讀模式
SELECT MESSAGE FROM V$DATAGUARD_STATUS; 查看DATA GUARD 狀態
recover managed standby database disconnect from session; 只讀還原管理模式
SELECT THREAD#,LOW_SEQUENCE#,HIGH_SEQUENCE# FROM V$ARCHIVE_GAP; 查詢日誌GAP
---測試看日誌是否傳送成功。
主庫：
Sql>alter system switch logfile;
Sql> select max(SEQUENCE#) from v$archived_log;
備庫：
Sql> /
select FIRST_TIME,NEXT_TIME, APPLIED,SEQUENCE# from v$archived_log order by SEQUENCE#;
SELECT MAX(R.SEQUENCE#) LAST_SEQ_RECD, MAX(L.SEQUENCE#) LAST_SEQ_SENT FROM V$ARCHIVED_LOG R, V$LOG L WHERE R.DEST_ID=2 AND L.ARCHIVED='YES';
SELECT NAME FROM V$ARCHIVED_LOG WHERE THREAD#=1 AND DEST_ID=1 AND SEQUENCE# BETWEEN 85 AND 86;
檢查STANDBY LOG分配情況
select GROUP#,THREAD#,SEQUENCE#,USED,ARCHIVED,STATUS from v$standby_log;
查詢數據庫DG工作模式
SELECT NAME,OPEN_MODE,DATABASE_ROLE,PROTECTION_MODE FROM V$DATABASE;
修改主庫爲最大可用模式
ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE AVAILABILITY;
修修主庫爲最大保護模式 啓動順序爲先啓備庫，再啓主庫， 關閉順序爲先關主庫，再關備庫
ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE PROTECTION;
修改主庫爲最大性能模式
ALTER DATABASE SET STANDBY DATABASE TO MAXIMIZE PERFORMANCE;
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=enable; 啓用
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=reset; 停用
alter database add logfile group 1 ('/mesdata/datafile/onlinelog/group019') size 200M ;
alter database add logfile group 3 size 200M ;
alter database add logfile group 4 size 200M ;
alter database add logfile group 6 size 200M ;
alter database add logfile group 13 size 200M ;
alter database add logfile group 14 size 200M ;
alter database add logfile group 15 size 200M ;
alter database add logfile group 16 size 200M ;
alter database add logfile group 17 size 200M ;
alter database add standby logfile group 9 ('/mesarch/onlinelog/group09.log') size 200M ;
alter database add standby logfile group 10 size 200M ;
alter database add standby logfile group 11 size 200M ;
alter database add standby logfile group 12 size 200M ;
alter database add standby logfile group 13 size 200M ;
alter database add standby logfile group 14 size 200M ;
alter database add standby logfile group 15 size 200M ;
alter database add standby logfile group 16 size 200M ;
alter database add standby logfile group 17 size 200M ;