oracle ckpt檢查點型別（增量及常規完全檢查點)checkpoint

 

SQL> alter system set log_checkpoints_to_alert=true;

--啟用在alert中開啟檢查點事件記錄功能

System altered.

-bash-3.2$ tail -f alert_orcl.log --檢視alert
Wed Aug 18 13:53:43 2010
Completed: alter tablespace users end backup
Wed Aug 18 15:52:26 2010
create tablespace test datafile '/oracle/oradata/orcl/test01.dbf' size 10m
Wed Aug 18 15:52:26 2010
Completed: create tablespace test datafile '/oracle/oradata/orcl/test01.dbf' size 10m
Wed Aug 18 16:27:59 2010
ALTER SYSTEM: Flushing buffer cache
Wed Aug 18 16:47:43 2010
ALTER SYSTEM SET log_checkpoints_to_alert=TRUE SCOPE=BOTH;

 

--這是執行alter system switch logfile發生的檢查事件
Wed Aug 18 16:48:11 2010 --發生時間

--發生檢查點的rba及scn
Beginning log switch checkpoint up to RBA [0xf.2.10], SCN: 753891
Thread 1 advanced to log sequence 15
  Current log# 2 seq# 15 mem# 0: /oracle/oradata/orcl/redo02.log

 

--又執行一次alter system switch logfile
Wed Aug 18 16:48:39 2010
Beginning log switch checkpoint up to RBA [0x10.2.10], SCN: 753901
Thread 1 advanced to log sequence 16
  Current log# 3 seq# 16 mem# 0: /oracle/oradata/orcl/redo03.log

--來了一次完全檢查點

---alter system checkpoint
Wed Aug 18 16:49:30 2010
Beginning global checkpoint up to RBA [0x10.2.10], SCN: 753918

--這下同時把上面的檢查點工作完成了
Completed checkpoint up to RBA [0x10.2.10], SCN: 753918
Completed checkpoint up to RBA [0x10.2.10], SCN: 753901
Completed checkpoint up to RBA [0xf.2.10], SCN: 753891

 

說明：

 檢查點是一種事件，它的觸發（發生）到完成檢查點，不是同步的，是需要一定的時間

所以這個調優很重要了