一. 問題描述：

       BI分析部門反映夜間拉取的ORACLE備庫資料和業務部門匯入主庫的資料不一致，之間相差近2個小時。

二. 問題分析：

     第一反映備庫歸檔有GAP，主備庫延遲，經過查詢發現主備庫歸檔並無延遲

SQL> select process, status, sequence# , ACTIVE_AGENTS from v$managed_standby;

PROCESS   STATUS        SEQUENCE# ACTIVE_AGENTS
--------- ------------ ---------- -------------
ARCH      CLOSING            1468             0
ARCH      CLOSING            1469             0
ARCH      CONNECTED             0             0
ARCH      CLOSING            1470             0
RFS       IDLE                  0             0
RFS       IDLE               1471             0
RFS       IDLE                  0             0
MRP0      WAIT_FOR_LOG       1471            41
RFS       IDLE                  0             0

9 rows selected.
 

     第二種可能性夜間網路延遲等故障導致主備庫資料不一致，經過檢查alert等並未發現任何異常      手工在主庫做測試新建test表，插入資料.....發現確實未同步到備庫，且一切正常無任何報錯等。

主庫測試：
SQL> create table tevis (id number(10),
  2  name varchar2(10));
Table created.
SQL> insert into tevis values(1, 'anhui');
1 row created.
SQL> commit;
Commit complete.
SQL> 
備庫查詢：
SQL> select * from tevis;
select * from evisevis           *
ERROR at line 1:
ORA-00942: table or view does not exist
SQL> 
 

   查詢備庫v$dataguard_stats檢視：

SQL> select * from v$dataguard_stats ;
NAME                             VALUE                UNIT                           TIME_COMPUTED                  DATUM_TIME
-------------------------------- -------------------- ------------------------------ ------------------------------ ------------------------------
transport lag                    +00 00:00:00         day(2) to second(0) interval   09/04/2017 16:03:23            09/04/2017 16:03:22
apply lag                        +00 04:02:49         day(2) to second(0) interval   09/04/2017 16:03:23            09/04/2017 16:03:22
apply finish time                +00 00:00:00.290     day(2) to second(3) interval   09/04/2017 16:03:23
estimated startup time           9                    second                         09/04/2017 16:03:23
SQL> 
 

發現apply log竟已經達到了4h只多。 手工  alter system switch logfile; 發現備庫測試資料tevis表資料已經同步，而且v$dataguard_stats中apply log 為零。 因此：導致主備庫延遲的原因為 not apply current logfile

三. 問題處理：

SQL> alter  database recover managed  standby  database  cancel;
Database altered.
SQL> alter database recover managed standby database using current logfile disconnect;
Database altered.
SQL>

    再去查詢檢視v$dataguard_stats

SQL> select * from v$dataguard_stats;
NAME                             VALUE                UNIT                           TIME_COMPUTED                  DATUM_TIME
-------------------------------- -------------------- ------------------------------ ------------------------------ ------------------------------
transport lag                    +00 00:00:00         day(2) to second(0) interval   09/04/2017 16:10:54            09/04/2017 16:10:52
apply lag                        +00 00:00:00         day(2) to second(0) interval   09/04/2017 16:10:54            09/04/2017 16:10:52
apply finish time                                     day(2) to second(3) interval   09/04/2017 16:10:54
estimated startup time           9                    second                         09/04/2017 16:10:54
SQL>