OGG的extract进程checkpoint时间点回到1988-01-01 00:00:00故障处理

Extract进程（SEXTR01）状态为running，但是Lag at Chkpt却达到5个多小时，且时间一直在增长，根本就不抽取新日志，状态信息如下

1、故障现象
    Extract进程（SEXTR01）状态为running，但是Lag at Chkpt却达到5个多小时，且时间一直在增长，根本就不抽取新日志，状态信息如下：

GGSCI (caXXadgdb) 21> info all

Program    Status      Group      Lag at Chkpt  Time Since Chkpt

MANAGER    RUNNING                                         

EXTRACT    RUNNING    DPEYWGL    00:00:00      00:00:04 

EXTRACT    RUNNING    SEXTR01    05:14:58      00:00:03 
 

2、故障分析
2.1 debug一下进程状态信息
GGSCI (caXXadgdb) 23> info sextr01, showch debug

 

EXTRACT    SEXTR01  Last Started 2015-01-25 22:51  Status RUNNING

Checkpoint Lag      05:21:26 (updated 00:00:04 ago)

Log Read Checkpoint  Oracle Redo Logs

                    2015-01-25 18:05:16  Thread 1, Seqno 5554, RBA 611373536

                    SCN 3126.136656462 (13426204423758)

Log Read Checkpoint  Oracle Redo Logs

                    1988-01-01 00:00:00  Thread 2, Seqno 4016, RBA 1024

                    SCN 44527.110828288 (191242119617280)

 

 

Current Checkpoint Detail:

 

Read Checkpoint #1

……

 

Read Checkpoint #2

 

  Oracle Threaded Redo Log

 

  Startup Checkpoint (starting position in the data source):

    Thread #: 2

    Sequence #: 4015

    RBA: 640984080

    Timestamp: 2015-01-25 18:03:51.000000

    SCN: 3126.136602577 (13426204369873)

    Redo File: +DGROUP1/caXXdb/onlinelog/group_15.267.799673791

 

  Recovery Checkpoint (position of oldest unprocessed transaction in the data source):

    Thread #: 2

    Sequence #: 4015

    RBA: 640984080

    Timestamp: 2015-01-25 18:03:51.000000

    SCN: 3126.136602577 (13426204369873)

    Redo File: +DGROUP1/caXXdb/onlinelog/group_15.267.799673791

 

  Current Checkpoint (position of last record read in the data source):

    Thread #: 2

    Sequence #: 4016

    RBA: 1024

    Timestamp: 1988-01-01 00:00:00.000000

    SCN: 44527.110828288 (191242119617280)

    Redo File: +DGROUP1/caXXdb/onlinelog/group_16.266.799673793

……
 

 

从这里发现一个不可思议的问题：

      Thread #: 2的current checkpoint 的timestamp竟然是1988-01-0100:00:00.000000，SCN的十进制数，竟然为191242119617280，远远大于当前数据库的SCN，多出一位数。

      时间倒退，SCN号反而大涨，时间还那么有个性。这个问题挺有意思。

2.2 view extract进程的report
    使用view report sextr01查看进程的报告，提示有ERROR，thread#2 4016 archive log 不能打开。（由于笔者没有将信息复制下来，所以当时的状态只能这么描述了），但是4016号archivelog实际物理文件是存在的，而且权限正常。

2.3 将进程停止下来，showch其状态
GGSCI (calladgdb) 24>stop sextr01

GGSCI (calladgdb) 25> info SEXTR01, showch

EXTRACT    SEXTR01  Last Started 2015-01-26 01:00  Status STOPPED

Checkpoint Lag      06:56:55 (updated 00:00:58 ago)

Log Read Checkpoint  Oracle Redo Logs

                    2015-01-25 18:05:16  Thread 1, Seqno 5554, RBA 611373536

                    SCN 3126.136656462 (13426204423758)

Log Read Checkpoint  Oracle Redo Logs

                    1988-01-01 00:00:00  Thread 2, Seqno 4016, RBA 1024

                    SCN 44527.110828288 (191242119617280)

 

Current Checkpoint Detail:

 

Read Checkpoint #1

……

 

Read Checkpoint #2

 

  Oracle Threaded Redo Log

 

  Startup Checkpoint (starting position in the data source):

    Thread #: 2

    Sequence #: 4015

    RBA: 640984080

    Timestamp: 2015-01-25 18:03:51.000000

    SCN: 3126.136602577 (13426204369873)

    Redo File: +DGROUP1/caXXdb/onlinelog/group_15.267.799673791

 

  Recovery Checkpoint (position of oldest unprocessed transaction in the data source):

    Thread #: 2

    Sequence #: 4015

    RBA: 640984080

    Timestamp: 2015-01-25 18:03:51.000000

    SCN: 3126.136602577 (13426204369873)

    Redo File: +DGROUP1/caXXdb/onlinelog/group_15.267.799673791

 

  Current Checkpoint (position of last record read in the data source):

    Thread #: 2

    Sequence #: 4016

    RBA: 1024

    Timestamp: 1988-01-01 00:00:00.000000

    SCN: 44527.110828288 (191242119617280)

    Redo File: +DGROUP1/caXXdb/onlinelog/group_16.266.799673793

……