奇怪的OGG問題：DBLOGREADER mode: (308) ORA-00308

      一日，進行資料庫引數變更。變更需要重啟資料庫例項，不可避免的，RAC一個節點上部署的OGG的extract程式不可避免受到了影響。我們並未正常關閉抽取，於是抽取程式崩潰。

      手動啟動後，發現抽取程式並不能正常抽取事務, 日誌中提示：
     DBLOGREADER mode: (308) ORA-00308

2021-01-27 22:41:02  INFO    OGG-02089  Oracle GoldenGate Capture for Oracle, e_hisdb.prm:  Source redo compatibility version is: 11.2.0.4.0.

2021-01-27 22:41:02  INFO    OGG-00546  Oracle GoldenGate Capture for Oracle, e_hisdb.prm:  Default thread stack size: 196608.

2021-01-27 22:41:02  INFO    OGG-00547  Oracle GoldenGate Capture for Oracle, e_hisdb.prm:  Increasing thread stack size from 196608 to 1048576.

2021-01-27 22:41:02  INFO    OGG-01513  Oracle GoldenGate Capture for Oracle, e_hisdb.prm:  Positioning to (Thread 2) Sequence 48955, RBA 4553232, SCN 4.77637361 (17257506545).

2021-01-27 22:41:02  INFO    OGG-01513  Oracle GoldenGate Capture for Oracle, e_hisdb.prm:  Positioning to (Thread 1) Sequence 42299, RBA 273158160, SCN 4.77482275 (17257351459).

2021-01-27 22:42:18  ERROR   OGG-00446  Oracle GoldenGate Capture for Oracle, e_hisdb.prm:  Opening file +ARCH/archive/1_42299_927030046.dbf in DBLOGREADER mode: (308) ORA-00308: cannot open archived log '+ARCH/archive/1_42299_927030046.dbf'

ORA-17503: ksfdopn:2 Failed to open file +ARCH/archive/1_42299_927030046.dbf

ORA-15173: entry '1_42299_927030046.dbf' does not exist in directory 'archive'

Not able to establish initial position for sequence 42299, rba 273158160.

讓我感覺到奇怪的是, ，兩個例項中抽取程式的歸檔日誌的sequenceno正好與實際相反，thread 1應該是 48955， thread 2是42299,  實際上，thread 1的42299號日誌早就不在了。

而在OGG的命令列中，extract程式的thread也是不正常的

EXTRACT    E_HISDB   Last Started 2021-01-27 23:02   Status ABENDED

Checkpoint Lag       00:40:41 (updated 00:07:31 ago)

Log Read Checkpoint  Oracle Redo Logs

                     2021-01-27 22:22:49  Thread 1, Seqno 48955, RBA 4553728

                     SCN 4.77637361 (17257506545)

Log Read Checkpoint  Oracle Redo Logs

                     2021-01-27 22:23:06  Thread 1, Seqno 42299, RBA 319420708

                     SCN 4.77649758 (17257518942)

從MOS中也找不到存在類似的問題。

只好嘗試指定SCN啟動

alter extract e_hisdb  scn 17257518942

start extract e_hisdb

GGSCI (hisdb2) 6> info all

Program     Status      Group       Lag at Chkpt  Time Since Chkpt

MANAGER     RUNNING                                           

EXTRACT     STARTING    E_HISDB     00:00:00      00:00:06    

EXTRACT     RUNNING     P_HISDB     00:00:00      00:00:05    

GGSCI (hisdb2) 7> info e_hisdb

EXTRACT    E_HISDB   Last Started 2021-01-27 23:11   Status RUNNING

Checkpoint Lag       00:00:00 (updated 00:00:09 ago)

Process ID           22217156

Log Read Checkpoint  Oracle Redo Logs

                     First Record         Thread 2, Seqno 42299, RBA 319413776

                     SCN 4.77649758 (17257518942)

Log Read Checkpoint  Oracle Redo Logs

                     First Record         Thread 1, Seqno 48955, RBA 4693008

                     SCN 4.77649758 (17257518942)

終於正常啟動。

百思不得其解。