转: OGG Checkpoint 详解

1.

OGG Checkpoint 详解

定位中断的位置，下次启动从中断的位置开始恢复。

1.target  端配置；

2.一条记录对应一个replicat

一. Extract Checkpoints

 (1) Extract read checkpoints

         （1） Startup checkpoint   --ogg启动的时候创建

          当Extract 进程启动的时候，会创建startup checkpoint，用来记录此时record的相关信息。该     checkpoint    是第一个checkpoint。
          startup checkpoint的统计信息包含如下内容：
        （1） Thread #: 创建checkpoint 的thread编号。
        （2） Sequence #:创建checkpoint 时对应的sequence 号码。  --list archive log;
         （3） RBA: 创建checkpoint 时，redo log 里面record 的relative byte address。
        （4）Timestamp:  创建checkpoint 时record对应的timestamp。
        （5）SCN: 创建checkpoint 时 record 对应的system change number 。
        （6）Redo File: 创建checkpoint 时record对应的事务日志路径。

 2 ) Recovery checkpoint

      recover checkpoint 记录的是data source（online redo log 或者归档中）中Extract 最久没处理的record的位置。 该checkpoint 的统计信息和startup checkpoint一样。

3) Current checkpoint

current checkpoint 是data source中Extract 最后一次读取的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  会变，说明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

该checkpoint包含如下信息：
 （1）Sequence #: checkpoint 正在写的trail 文件的序列号。
 （2）RBA: 创建checkpoint 时trail文件里record 的relative byte address。
 （3）Timestamp: 创建checkpoint 时record对应的timestamp。
 （4）Extract trail: trail 文件的路径。
 （5）Trail Type: 标识trail 文件类型。有2个值：
EXTTRAIL：表示该trail 是本地的trail，文件由OGG进程直接写如本地disk。
RMTTRAIL：表示是远程的trail，该文件不会写入本地的磁盘，而是传到远端的的OGG上，在有远端OGG的collector 进程写disk。
比如pump 进程，里面就会写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):  --最后一次读取文件的位置
    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是否有变化

REPLICAT   REP1      Last Started 2014-12-27 14:07   Status RUNNING

Checkpoint Lag       00:00:00 (updated 00:00:08 ago)

Process ID             26088

Log Read Checkpoint  File /us01/zt/dirdat/lt000004

 2014-12-27 16:49:03.408880   RBA 1755

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

停的时候确保两边都事物都提交了。 info 一下看看

 ②. data dump进程：将队列数据发送到目标 

 好处：① .预防网络和源库的故障；

           ②. 可以对数据进行过来和转换；

           ③.synchronize方式从多个源库上合并数据到一个中心库；

           ④. synchronize方式将一个源库数据传到多个目标库;

2.

Checkpoint table有两种类型：主表和辅助表。主表根据用户定义名称来来创建，辅助表会自动创建。辅助表就是transaction table。名称是checkpoint table名上加_LOX。

SQL> conn ogg/ogg

Connected.

SQL>

SQL> select table_name from user_tables;

TABLE_NAME

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

CKKPOINT_LOX

CKKPOINT

<spancalibri',sans-serif; color:yellow?="">SQL>  

---

Checkpoint table配置方法：

(1):在./GLOBALS文件里添加checkpoint 表名

GGSCI(suys1) 1> view param ./GLOBALS

ggschema ogg

checkpointtableogg.checkpointtab

GGSCI (suys1) 2>

(2):连上DB，创建checkpoint表

GGSCI(suys1) 85> dblogin userid ogg, password ogg

Successfullylogged into database.

GGSCI(suys1) 86> add checkpointtable ogg. checkpointtab

Successfully created checkpoint table ogg.checkpointtab.

--生成这个检查点记录表

(3):验证

conn ggs/

SQL> select * from checkpoint; GROUP_NA GROUP_KEY  SEQNO    RBA AUDIT_TS                      CREATE_TS    LAST_UPDATE_ CURRENT_DIR -------- ---------- ------ ----------------------------------- ------------ ------------ -------------- REP1    3987940558     12   1564 2011-11-17 17:21:55.471376    17-NOV-11   17-NOV-11    /u01/ggate

以上就介绍了OGG checkpoint table 说明，包括了方面的内容，希望对Oracle有兴趣的朋友有所帮助。