┌─────────────────────────────────────────────────────────────────────┐
│                    Oracle DataGuard 架构                             │
├─────────────────────────────────────────────────────────────────────┤
│                                                                     │
│   ┌──────────────────┐                    ┌──────────────────┐     │
│   │   主库 (Primary)  │◄────── 归档日志 ───►│   备库 (Standby)  │     │
│   │                  │    (ARCH/LGWR)     │                  │     │
│   │  ┌────────────┐  │                    │  ┌────────────┐  │     │
│   │  │ 生产业务   │  │                    │  │ 日志应用    │  │     │
│   │  │ 读写操作   │  │                    │  │ (MRP/LSP)   │  │     │
│   │  └────────────┘  │                    │  └────────────┘  │     │
│   │                  │                    │                  │     │
│   │  归档模式         │                    │  实时/延迟应用   │     │
│   │  FORCE LOGGING   │                    │  只读打开        │     │
│   └──────────────────┘                    └──────────────────┘     │
│                                                                     │
│   保护模式：                                                        │
│   ├── 最大性能 (Maximum Performance) - 异步传输，零性能影响          │
│   ├── 最大可用 (Maximum Availability) - 同步/异步自动切换            │
│   └── 最大保护 (Maximum Protection) - 强制同步，零数据丢失           │
│                                                                     │
└─────────────────────────────────────────────────────────────────────┘

-- 1. 确认主库处于归档模式
SELECT log_mode FROM v$database;
-- 结果应为 ARCHIVELOG

-- 2. 开启强制日志
ALTER DATABASE FORCE LOGGING;

-- 3. 配置主库参数
ALTER SYSTEM SET LOG_ARCHIVE_CONFIG='DG_CONFIG=(ORCL,ORCLDG)' SCOPE=BOTH;
ALTER SYSTEM SET LOG_ARCHIVE_DEST_1='LOCATION=/u01/app/oracle/arch VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=ORCL' SCOPE=SPFILE;
ALTER SYSTEM SET LOG_ARCHIVE_DEST_2='SERVICE=ORCLDG LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=ORCLDG' SCOPE=BOTH;
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_1=ENABLE SCOPE=BOTH;
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE SCOPE=BOTH;
ALTER SYSTEM SET REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE SCOPE=SPFILE;
ALTER SYSTEM SET FAL_SERVER=ORCLDG SCOPE=BOTH;
ALTER SYSTEM SET FAL_CLIENT=ORCL SCOPE=BOTH;
ALTER SYSTEM SET DB_FILE_NAME_CONVERT='/u01/app/oracle/oradata/ORCLDG','/u01/app/oracle/oradata/ORCL' SCOPE=SPFILE;
ALTER SYSTEM SET LOG_FILE_NAME_CONVERT='/u01/app/oracle/oradata/ORCLDG','/u01/app/oracle/oradata/ORCL' SCOPE=SPFILE;
ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT=AUTO SCOPE=BOTH;

# 1. 配置备库监听器和网络服务名
# listener.ora
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = ORCLDG)
      (ORACLE_HOME = /u01/app/oracle/product/19c/dbhome_1)
      (SID_NAME = ORCLDG)
    )
  )

# tnsnames.ora
ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = primary_host)(PORT = 1521))
    (CONNECT_DATA = (SERVER = DEDICATED)(SERVICE_NAME = ORCL))
  )

ORCLDG =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = standby_host)(PORT = 1521))
    (CONNECT_DATA = (SERVER = DEDICATED)(SERVICE_NAME = ORCLDG))
  )

# 2. 使用 RMAN 复制数据库
$ rman target sys/password@ORCL auxiliary sys/password@ORCLDG

RMAN> DUPLICATE TARGET DATABASE
      FOR STANDBY
      FROM ACTIVE DATABASE
      DORECOVER
      SPFILE
        SET DB_UNIQUE_NAME='ORCLDG'
        SET LOG_ARCHIVE_DEST_2='SERVICE=ORCL LGWR ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=ORCL'
      NOFILENAMECHECK;

-- 备库启动到 MOUNT 状态
STARTUP MOUNT;

-- 开启实时应用
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT;

-- 或者延迟应用（如延迟 1 小时）
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DELAY 60 DISCONNECT;

-- ========== 主库操作 ==========
-- 1. 检查切换状态
SELECT switchover_status FROM v$database;
-- 应为 TO STANDBY

-- 2. 执行切换
ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN;

-- 3. 关闭并重启到 MOUNT
SHUTDOWN ABORT;
STARTUP MOUNT;

-- ========== 原备库操作 ==========
-- 1. 检查状态
SELECT switchover_status FROM v$database;
-- 应为 TO PRIMARY

-- 2. 切换为主库
ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;

-- 3. 打开新主库
ALTER DATABASE OPEN;

-- 4. 新备库开启日志应用
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT;

-- 1. 停止日志应用
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH FORCE;

-- 2. 检查日志应用情况
SELECT THREAD#, SEQUENCE#, APPLIED FROM V$ARCHIVED_LOG ORDER BY SEQUENCE#;

-- 3. 执行故障转移
ALTER DATABASE FAILOVER TO ORCLDG;

-- 4. 打开为新主库
ALTER DATABASE OPEN;

-- 5. 重建原主库（修复后）
-- 使用 RMAN DUPLICATE 或 Flashback Database

-- 查看日志传输延迟
SELECT 
    name,
    value,
    unit,
    time_computed
FROM v$dataguard_stats
WHERE name IN ('transport lag', 'apply lag', 'apply finish time');

-- 查看归档日志应用情况
SELECT 
    dest_name,
    status,
    error,
    gap_status
FROM v$archive_dest_status
WHERE dest_id <= 2;

-- 查看日志序列号同步
SELECT 
    max(sequence#) as primary_seq,
    (SELECT max(sequence#) FROM v$archived_log WHERE applied='YES') as standby_seq,
    max(sequence#) - (SELECT max(sequence#) FROM v$archived_log WHERE applied='YES') as gap
FROM v$archived_log
WHERE dest_id=1 AND archived='YES';

-- 备库以只读模式打开（需要 Active DataGuard 许可）
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
ALTER DATABASE OPEN;
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT;

-- 或者使用快照备库进行读写测试
ALTER DATABASE CONVERT TO SNAPSHOT STANDBY;
-- 执行测试操作...
ALTER DATABASE CONVERT TO PHYSICAL STANDBY;