oracle--DG查询同步

查询归档历史：

SELECT  FIRST_TIME,FIRST_CHANGE#,NEXT_CHANGE#, SEQUENCE# FROM V$LOG_HISTORY;

检查归档文件路径和创建信息

SELECT NAME,CREATOR,SEQUENCE#,APPLIED,COMPLETION_TIME  FROM V$ARCHIVED_LOG; 

查看进程的活动状态
V$MANAGED_STANDBY视图专用于显示物理Standby数据库相关进程的
当前状态，该视图中的列也很有特点，查看进程状态时，通常我们会关注
PROCESS、CLIENT_PROCESS、SEQUENC#和STATUS几列，例如：

SQL>  SELECT  PROCESS,CLIENT_PROCESS,SEQUENCE#,  STATUS  FROM
V$MANAGED_STANDBY;
PROCESS      CLIENT_P    SEQUENCE# STATUS
--------- -------- ---------- ------------
ARCH            ARCH                78     CLOSING
ARCH            ARCH                79    CLOSING
MRP0            N/A                    80    WAIT_FOR_LOG
RFS              LGWR                80    IDLE
RFS              ARCH                  0      IDLE
RFS              N/A                     0      IDLE 

相关说明：
PROCESS：进程名称，如ARCH、RFS、MRP0等。
CLIENT_P：对应的Primary数据库中的进程，如ARCH、LGWR等。
SEQUENCE#：归档序号。
STATUS：进程的当前状态，值较多，常见的有：
1）ALLOCATED：正准备连接Primary数据库。
2）ATTACHED：正在连接Primary数据库。
3）CONNECTED：已连接至Primary数据库。
4）IDLE：空闲中。
5）RECEIVING：归档文件接收中。
6）OPENING：归档文件处理中。
7）CLOSING：归档文件处理完，收尾中。
8）WRITING：REDO数据库写向归档文件中。
9）WAIT_FOR_LOG：等待新的REDO数据中。
10）WAIT_FOR_GAP：归档有中断，正等待中断的那部分REDO数据。
11）APPLYING_LOG：应用REDO数据中。

查看最后应用的归档

SELECT  THREAD#,  MAX(SEQUENCE#)  AS  "LAST_APPLIED_LOG" FROM V$LOG_HISTORY GROUP BY THREAD#;

THREAD# LAST_APPLIED_LOG
---------- ----------------
     1           3104

查看对应的应用状态
SELECT THREAD#, SEQUENCE#, APPLIED FROM V$ARCHIVED_LOG;
   THREAD#  SEQUENCE# APPLIED
---------- ---------- ---------
     1     3098 YES
     1     3099 YES
     1     3100 YES
     1     3101 YES
     1     3102 YES
     1     3103 YES
     1     3104 IN-MEMORY

查看物理Standby数据库未接收的日志文件

日志文件的发送是通过LOG_ARHIVE_DEST_N参数来控制，因此我们只需
要对比本地生成的归档和远端生成的归档间差异即可。例如：
select local.thread#,  local.sequence#  from  (select  thread#,  sequence#  from v$archived_log  where  dest_id=1)  local  where  local.sequence#  not  in    (select sequence# from v$archived_log where dest_id=2 and    thread# = local.thread#);
 
   THREAD#  SEQUENCE#
---------- ----------
     1     3098
     1     3099
     1     3100
     1     3101
     1     3102
     1     3103
     1     3104

监控日志应用服务

查询当前数据的基本信息（v$database信息）
select database_role,db_unique_name,open_mode,protection_mode,protection_level, switchover_status from v$database;

DATABASE_ROLE     DB_UNIQUE_NAME         OPEN_MODE
---------------- ------------------------------ --------------------
PROTECTION_MODE      PROTECTION_LEVEL      SWITCHOVER_STATUS
-------------------- -------------------- --------------------
PHYSICAL STANDBY standby_oracle01        MOUNTED
MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE  NOT ALLOWED

查看当前REDO应用和REDO传输服务的活动状态
查询物理Standby 数据库当前REDO应用和REDO传输服务的状态非
V$MANAGED_STANDBY视图莫属，例如：

 select  process,  status,  thread#,  sequence#,  block#,  blocks  from v$managed_standby;

PROCESS   STATUS      THREAD#  SEQUENCE#     BLOCK#     BLOCKS
--------- ------------ ---------- ---------- ---------- ----------
ARCH      CONNECTED        0       0          0      0
ARCH      CONNECTED        0       0          0      0
ARCH      CONNECTED        0       0          0      0
ARCH      CLOSING        1    3104       6144       1008
ARCH      CONNECTED        0       0          0      0
RFS      IDLE            0       0          0      0
RFS      IDLE            0       0          0      0
RFS      IDLE            1    3105       1596      1
MRP0      APPLYING_LOG        1    3105       1596     163840

检查应用模式（是否启用了实时应用）

物理Standby数据库查询V$ARCHIVE_DEST_STATUS视图，如果打开了实
时应用，则RECOVERY_MODE列会显示为：MANAGED REAL TIME APPLY，

RECOVERY_MODE
-----------------------
IDLE

Data Guard事件（V$DATAGUARD_STATUS）

SQL> SELECT MESSAGE FROM V$DATAGUARD_STATUS;

MESSAGE
--------------------------------------------------------------------------------
ARC0: Archival started
ARC1: Archival started
ARC2: Archival started
ARC3: Archival started
ARC3: Becoming the 'no FAL' ARCH
ARC2: Becoming the heartbeat ARCH
ARC2: Becoming the active heartbeat ARCH
ARC4: Archival started
Managed Standby Recovery not using Real Time Apply
RFS[1]: Assigned to RFS process 27418
ARC3: Beginning to archive thread 1 sequence 3102 (14245665-14245874)

MESSAGE
--------------------------------------------------------------------------------
ARC3: Completed archiving thread 1 sequence 3102 (0-0)
Primary database is in MAXIMUM PERFORMANCE mode
RFS[2]: Assigned to RFS process 27420
Attempt to start background Managed Standby Recovery process
MRP0: Background Managed Standby Recovery process started
Managed Standby Recovery starting Real Time Apply
Clearing online redo logfile 1 /u01/app/oracle/oradata/oracle01/redo01.log
Clearing online redo logfile 1 complete
Clearing online redo logfile 2 /u01/app/oracle/oradata/oracle01/redo02.log
Clearing online redo logfile 2 complete
Clearing online redo logfile 3 /u01/app/oracle/oradata/oracle01/redo03.log

MESSAGE
--------------------------------------------------------------------------------
Clearing online redo logfile 3 complete
Clearing online redo logfile 9 /u01/app/oracle/oradata/oracle01/redo05a.log
Clearing online redo logfile 9 complete
Media Recovery Log /u01/app/oracle/product/11.2.0/db_1/dbs/archivelog/1_3102_100
0748999.dbf

Media Recovery Waiting for thread 1 sequence 3103 (in transit)
ARC3: Beginning to archive thread 1 sequence 3103 (14245874-14245930)
ARC3: Completed archiving thread 1 sequence 3103 (0-0)
Media Recovery Waiting for thread 1 sequence 3104 (in transit)
MRP0: Background Media Recovery cancelled with status 16037

MESSAGE
--------------------------------------------------------------------------------
Managed Standby Recovery not using Real Time Apply
MRP0: Background Media Recovery process shutdown
Managed Standby Recovery Canceled
Attempt to start background Managed Standby Recovery process
MRP0: Background Managed Standby Recovery process started
Managed Standby Recovery starting Real Time Apply
Media Recovery Waiting for thread 1 sequence 3104 (in transit)
ARC3: Beginning to archive thread 1 sequence 3104 (14245930-14250924)
ARC3: Completed archiving thread 1 sequence 3104 (0-0)
Media Recovery Waiting for thread 1 sequence 3105 (in transit)

41 rows selected.

设置RECOVER并行度
在介质恢复或REDO应用期间，都需要读取重做日志文件，默认都是串行
复，我们可以在执行RECOVER的时候加上PARALLEL子句来指定并行度，
高读取和应用的性能，例如：

SQL> RECOVER STANDBY DATABASE PARALLEL 2 ;  

查看保护模式

SQL> select protection_mode,protection_level from v$database;
PROTECTION_MODE            PROTECTION_LEVEL
-------------------- --------------------
MAXIMUM PERFORMANCE    MAXIMUM PERFORMANCE