OGG 11g Checkpoint 詳解

OGG Checkpoint 詳解

定位中斷的位置，下次啟動從中斷的位置開始恢復。

1.target  端配置；

2.一條記錄對應一個replicat

一. Extract Checkpoints

 (1) Extract read checkpoints

         （1） Startup checkpoint   --ogg啟動的時候建立

          當Extract 程式啟動的時候，會建立startup checkpoint，用來記錄此時record的相關資訊。該     checkpoint    是第一個checkpoint。
          startup checkpoint的統計資訊包含如下內容：
        （1） Thread #: 建立checkpoint 的thread編號。
        （2） Sequence #:建立checkpoint 時對應的sequence 號碼。  --list archive log;
        （3） RBA: 建立checkpoint 時，redo log 裡面record 的relative byte address。
        （4）Timestamp:  建立checkpoint 時record對應的timestamp。
        （5）SCN: 建立checkpoint 時 record 對應的system change number 。
        （6）Redo File: 建立checkpoint 時record對應的事務日誌路徑。

 2 ) Recovery checkpoint

      recover checkpoint 記錄的是data source（online redo log 或者歸檔中）中Extract 最久沒處理的record的位置。 該checkpoint 的統計資訊和startup checkpoint一樣。

3) Current checkpoint

current checkpoint 是data source中Extract 最後一次讀取的record的位置。

GGSCI (ogg02) 4>  info ext1

EXTRACT    EXT1      Last Started 2014-12-27 17:42   Status RUNNING
Checkpoint Lag          00:00:00 (updated 00:00:04 ago)
Process ID                31621
Log Read Checkpoint  Oracle Redo Logs
                     2014-12-27 18:06:05  Seqno 15, RBA 18128896
                     SCN 0.1142344 (1142344)

Seqno  和 RBA  會變，說明ogg是在工作的。

GGSCI (ogg02) 5>  info ext1,showch

EXTRACT    EXT1      Last Started 2014-12-27 17:42   Status RUNNING
Checkpoint Lag       00:00:00 (updated 00:00:00 ago)
Process ID           31621
Log Read Checkpoint  Oracle Redo Logs
                     2014-12-27 18:11:06  Seqno 15, RBA 18188800
                     SCN 0.1142472 (1142472)


Current Checkpoint Detail:

Read Checkpoint #1

  Oracle Redo Log

  Startup Checkpoint (starting position in the data source):
    Thread #: 1
    Sequence #: 11
    RBA: 7646224
    Timestamp: 2014-12-27 16:20:48.000000
    SCN: 0.1136079 (1136079)
    Redo File: /oradata/ogg02/redo02.log

  Recovery Checkpoint (position of oldest unprocessed transaction in the data source):
    Thread #: 1
    Sequence #: 15
    RBA: 18187792
    Timestamp: 2014-12-27 18:09:41.000000
    SCN: 0.1142443 (1142443)
    Redo File: /oradata/ogg02/redo03.log

  Current Checkpoint (position of last record read in the data source):
    Thread #: 1
    Sequence #: 15
    RBA: 18188800
    Timestamp: 2014-12-27 18:11:06.000000
    SCN: 0.1142472 (1142472)
    Redo File: /oradata/ogg02/redo03.log

Write Checkpoint #1

  GGS Log Trail

  Current Checkpoint (current write position):
    Sequence #: 4
    RBA: 1755
    Timestamp: 2014-12-27 18:11:43.251745
    Extract Trail: /u01/zt/dirdat/lt
    Trail Type: RMTTRAIL

Header:
  Version = 2
  Record Source = A
  Type = 10
  # Input Checkpoints = 1
  # Output Checkpoints = 1

File Information:
  Block Size = 2048
  Max Blocks = 100
  Record Length = 2048
  Current Offset = 0

Configuration:
  Data Source = 3
  Transaction Integrity = 1
  Task Type = 0

Status:
  Start Time = 2014-12-27 17:42:32
  Last Update Time = 2014-12-27 18:11:43
  Stop Status = A
  Last Result = 400

二.Extract write checkpoints

該checkpoint包含如下資訊：
（1）Sequence #: checkpoint 正在寫的trail 檔案的序列號。
（2）RBA: 建立checkpoint 時trail檔案裡record 的relative byte address。
（3）Timestamp: 建立checkpoint 時record對應的timestamp。
（4）Extract trail: trail 檔案的路徑。
（5）Trail Type: 標識trail 檔案型別。有2個值：
EXTTRAIL：表示該trail 是本地的trail，檔案由OGG程式直接寫如本地disk。
RMTTRAIL：表示是遠端的trail，該檔案不會寫入本地的磁碟，而是傳到遠端的的OGG上，在有遠端OGG的collector 程式寫disk。 
比如pump 程式，裡面就會寫RMTTRAIL。

-----------------------------------------------------------------------------------------

target 端

GGSCI (ogg04) 1>  info rep1

REPLICAT   REP1      Last Started 2014-12-27 14:07   Status RUNNING
Checkpoint Lag         00:00:00 (updated 00:00:01 ago)
Process ID               26088
Log Read Checkpoint  File /u01/zt/dirdat/lt000004
                     2014-12-27 16:49:03.408880  RBA 1755

GGSCI (ogg04) 2>  info rep1,showch

REPLICAT   REP1      Last Started 2014-12-27 14:07   Status RUNNING
Checkpoint Lag         00:00:00 (updated 00:00:07 ago)
Process ID               26088
Log Read Checkpoint  File /u01/zt/dirdat/lt000004
                     2014-12-27 16:49:03.408880  RBA 1755


Current Checkpoint Detail:

Read Checkpoint #1

  GGS Log Trail

  Startup Checkpoint (starting position in the data source):
    Sequence #: 3
    RBA: 20259
    Timestamp: 2014-12-27 14:06:57.000000
    Extract Trail: /u01/zt/dirdat/lt

  Current Checkpoint (position of last record read in the data source):  --最後一次讀取檔案的位置
    Sequence #: 4
    RBA: 1755
    Timestamp: 2014-12-27 16:49:03.408880
    Extract Trail: /u01/zt/dirdat/lt

Header:
  Version = 2
  Record Source = A
  Type = 1
  # Input Checkpoints = 1
  # Output Checkpoints = 0

File Information:
  Block Size = 2048
  Max Blocks = 100
  Record Length = 2048
  Current Offset = 0

Configuration:
  Data Source = 0
  Transaction Integrity = -1
  Task Type = 0

Database Checkpoint:
  Checkpoint table = ggs.checkpoint
  Key = 982417365 (0x3a8e7fd5)
  Create Time = 2014-12-27 10:46:19

Status:
  Start Time = 2014-12-27 14:07:31
  Last Update Time = 2014-12-27 17:03:30
  Stop Status = A
  Last Result = 400

 GGSCI (ogg04) 3> info rep1    --看rba是否有變化

 

轉：http://blog.csdn.net/zhengwei125/article/details/46503403