[20190312]關於增量檢查點的疑問(補充).txt
阿新 • • 發佈：2019-03-14
rtc erp http 補充 where rtu 產生 odr osd
1.環境:
SCOTT@book> @ ver1
PORT_STRING VERSION BANNER
------------------- -------------- ----------------------------------------------------------------------------
x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
--//寫一個腳本check.sql,以前寫的太復雜,簡單一點:
--// x$kcccp 記錄增量檢查點
$ cat check.sql
column "full checkpoint_rba" format a21
column low_rba format a20
column low_rba16 format a20
column on_disk_rba format a20
column on_disk_rba16 format a20
column rtckp_rba format a20
column diff_date format 9999999.99
rem column CPOSD_ono_disk_rba_scn format 99999999999999999999999999999999
column cpodt_on_disk_rba heading "檢查點隊列|on disk rba|時間戳|CPODT"
column cpods heading "檢查點隊列|on disk rba scn|CPODS"
column cphbt heading "檢查點心跳|CPHBT"
column current_sysdate heading "當前時間|SYSDATE"
set num 12
SELECT b.cplrba_seq || ‘.‘ || b.cplrba_bno || ‘.‘ || b.cplrba_bof "low_rba"
,b.cpodr_seq || ‘.‘ || b.cpodr_bno || ‘.‘ || b.cpodr_bof "on_disk_rba"
,b.CPODS "on_disk_rba_scn(CPODS)"
,TO_DATE (b.CPODT, ‘MM-DD-YYYY HH24:MI:SS‘) "on_disk_rba_time(CPODT)"
,a.rtckp_rba_seq || ‘.‘ || a.rtckp_rba_bno || ‘.‘ || a.rtckp_rba_bof
"full checkpoint_rba"
,a.rtckp_scn "full_checkpoint(rtckp_scn)"
,TO_DATE (a.rtckp_tim, ‘MM-DD-YYYY HH24:MI:SS‘)
"full_checkpoint_time_rtckp_tim"
,b.CPODS - a.rtckp_scn "diff_scn(on_disk_rdb-ch_scn)"
,a.rtcln "current_group"
,sysdate current_sysdate
,CPDRT
FROM x$kccrt a, x$kcccp b
WHERE a.rtnum = b.cptno AND A.INST_ID = b.inst_id;
2.測試:
SYS@book> shutdown abort ;
ORACLE instance shut down.
SYS@book> startup mount
ORACLE instance started.
Total System Global Area 643084288 bytes
Fixed Size 2255872 bytes
Variable Size 205521920 bytes
Database Buffers 427819008 bytes
Redo Buffers 7487488 bytes
Database mounted.
SYS@book> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /u01/app/oracle/archivelog/book/
Oldest online log sequence 787
Next log sequence to archive 789
Current log sequence 789
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
----------- ----------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
789.5775.0 789.5955.0 13278979623 2019-03-12 11:20:53 789.1890.16 13278977341 2019-03-12 10:52:50 2282 2 2019-03-12 11:21:42 12
--//看看日誌應用的起點是否從low_rba開始.
SYS@book> alter database open ;
Database altered.
--//查看alert.log日誌:
Beginning crash recovery of 1 threads
parallel recovery started with 23 processes
Started redo scan
Completed redo scan
read 90 KB redo, 12 data blocks need recovery
Started redo application at
Thread 1: logseq 789, block 5775
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>起點對應low_rba=789.5775.0
Recovery of Online Redo Log: Thread 1 Group 2 Seq 789 Reading mem 0
Mem# 0: /mnt/ramdisk/book/redo02.log
Completed redo application of 0.00MB
Completed crash recovery at
Thread 1: logseq 789, block 5956, scn 13278999624
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>結束對應on_disk_rba=789.5955.0加1個塊(512字節redo),scn號對應on_disk_rba_scn+1.
12 data blocks read, 12 data blocks written, 90 redo k-bytes read
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--//5955-5775 = 180,應用日誌180塊,日誌文件每塊512字節.
--//180*512/1024 = 90k,這些正好對上.
Tue Mar 12 11:23:26 2019
LGWR: STARTING ARCH PROCESSES
Tue Mar 12 11:23:26 2019
ARC0 started with pid=45, OS id=56804
ARC0: Archival started
LGWR: STARTING ARCH PROCESSES COMPLETE
ARC0: STARTING ARCH PROCESSES
Thread 1 advanced to log sequence 790 (thread open)
Thread 1 opened at log sequence 790
--//日誌切換使用新日誌.
Current log# 3 seq# 790 mem# 0: /mnt/ramdisk/book/redo03.log
Successful open of redo thread 1
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Tue Mar 12 11:23:27 2019
SMON: enabling cache recovery
--//也就是異常關閉後,crash recovery的起點從low_rba到on_disk_rba,完成後scn號+1,日誌塊號加1.日誌切換使用新日誌.
3.如果low_rba16=0xffffffff.ffffffff.ffff呢?
SYS@book> alter system checkpoint ;
System altered.
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 790.659.0 13279000486 2019-03-12 11:32:34 790.658.16 13279000485 2019-03-12 11:32:33 1 3 2019-03-12 11:32:35 0
5.65535
--//等一會執行:
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 790.678.0 13279000505 2019-03-12 11:32:53 790.658.16 13279000485 2019-03-12 11:32:33 20 3 2019-03-12 11:32:54 0
5.65535
--//你可以發現alter system checkpoint 後,如果沒有事務low_rba16=0xffffffff.ffffffff.ffff,而on_disk_rba一直在增加.而CPDRT=0.
--//似乎11g不知道為什麽在"空轉"(沒有事務產生的情況下)的情況,日誌也在不斷增加,不知道為什麽?
SYS@book> shutdown abort ;
ORACLE instance shut down.
SYS@book> startup mount
ORACLE instance started.
Total System Global Area 643084288 bytes
Fixed Size 2255872 bytes
Variable Size 205521920 bytes
Database Buffers 427819008 bytes
Redo Buffers 7487488 bytes
Database mounted.
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 790.705.0 13279000532 2019-03-12 11:33:20 790.658.16 13279000485 2019-03-12 11:32:33 47 3 2019-03-12 11:36:09 0
5.65535
--//可以發現這個時候low_rba16=0xffffffff.ffffffff.ffff,這個時候恢復的起點從那裏開始,實際上從on_disk_rba開始,或者講根本沒
--//有恢復,CPDRT=0也是佐證,雖然當時on_disk_rba還在不斷增加.
SYS@book> alter database open ;
Database altered.
--//查看alert.log:
Beginning crash recovery of 1 threads
parallel recovery started with 23 processes
Started redo scan
Completed redo scan
read 0 KB redo, 0 data blocks need recovery
Started redo application at
Thread 1: logseq 790, block 705, scn 13279000532
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>起點對應on_disk_rba=790.705.0
Recovery of Online Redo Log: Thread 1 Group 3 Seq 790 Reading mem 0
Mem# 0: /mnt/ramdisk/book/redo03.log
Completed redo application of 0.00MB
Completed crash recovery at
Thread 1: logseq 790, block 706, scn 13279020533
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>結束對應on_disk_rba=790.705.0加1個塊(512字節redo),scn號對應on_disk_rba_scn+1.
0 data blocks read, 0 data blocks written, 0 redo k-bytes read
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=> 日誌應用0K.
Tue Mar 12 11:39:33 2019
LGWR: STARTING ARCH PROCESSES
Tue Mar 12 11:39:33 2019
ARC0 started with pid=45, OS id=56980
ARC0: Archival started
LGWR: STARTING ARCH PROCESSES COMPLETE
ARC0: STARTING ARCH PROCESSES
Thread 1 advanced to log sequence 791 (thread open)
Thread 1 opened at log sequence 791
--//日誌切換使用新日誌.
Current log# 1 seq# 791 mem# 0: /mnt/ramdisk/book/redo01.log
Successful open of redo thread 1
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Tue Mar 12 11:39:34 2019
SMON: enabling cache recovery
4.我在原鏈接寫一個腳本:
SCOTT@book> create table t1 as select * from all_objects ;
Table created.
$ cat a.sql
alter system checkpoint;
alter system checkpoint;
alter system checkpoint;
@ check
update scott.t1 set object_name=object_name where rownum=1 ;
commit;
host sleep 3
@ check
SYS@book> @ a.sql
System altered.
System altered.
System altered.
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 791.21362.0 13279021797 2019-03-12 11:52:59 791.21362.16 13279021800 2019-03-12 11:53:00 -3 1 2019-03-12 11:53:01 0
5.65535
1 row updated.
Commit complete.
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.21363.0 791.21366.0 13279021805 2019-03-12 11:53:02 791.21362.16 13279021800 2019-03-12 11:53:00 5 1 2019-03-12 11:53:04 3
--//註意看發生事務前後的low_rba,on_disk_rba.不好描述,自己看.^_^.
--//一旦有事務產生,你可以發現low_rba不再是4294967295.4294967295.65535.
--//很奇怪不知道為什麽11g下在沒有事務的情況下會"空轉",這樣11g的日誌即使是很空閑的數據庫日誌增加也會比10g大.
5.看看10g的情況:
[email protected]:1521/test> @ ver1
PORT_STRING VERSION BANNER
------------------------------ -------------- ----------------------------------------------------------------
x86_64/Linux 2.4.xx 10.2.0.4.0 Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
[email protected]:1521/test> alter system checkpoint ;
System altered.
[email protected]:1521/test> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 1497.42866.0 14987614992 2019-03-12 11:55:37 1497.42866.16 14987615031 2019-03-12 11:57:34 -39 3 2019-03-12 11:57:35 0
5.65535
[email protected]:1521/test> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 1497.42866.0 14987614992 2019-03-12 11:55:37 1497.42866.16 14987615031 2019-03-12 11:57:34 -39 3 2019-03-12 11:58:29 0
5.65535
--//註意看執行時間2019-03-12 11:57:35 -2019-03-12 11:58:29 之間,沒有任何事務產生,on_disk_rba根本不變化.這樣10g日誌產生量
--//明顯比11g小.
6.我改上面的腳本check.sql:
--//最後加入host sleep 1.執行如下:
$ rlsql -s -l sys/oracle as sysdba <<EOF
> $(seq 100| xargs -I{} cat /home/oracle/sqllaji/check.sql)
> EOF
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24711.0 13279023352 2019-03-12 12:11:39 791.21362.16 13279021800 2019-03-12 11:53:00 1552 1 2019-03-12 12:11:41 8
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24712.0 13279023353 2019-03-12 12:11:40 791.21362.16 13279021800 2019-03-12 11:53:00 1553 1 2019-03-12 12:11:42 8
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24713.0 13279023354 2019-03-12 12:11:41 791.21362.16 13279021800 2019-03-12 11:53:00 1554 1 2019-03-12 12:11:43 8
--//在沒有事務的情況下.每秒scn增加1,日誌塊增加1,是否更我訪問這些內存"表"有關,換1個方式測試,取消check.sql後面的host sleep 1,建立腳本b.sql:
$ cat b.sql
@ check.sql
host sleep 30
@ check.sql
SYS@book> @ b.sql
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24852.0 13279023481 2019-03-12 12:13:41 791.21362.16 13279021800 2019-03-12 11:53:00 1681 1 2019-03-12 12:13:43 19
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24882.0 13279023511 2019-03-12 12:14:11 791.21362.16 13279021800 2019-03-12 11:53:00 1711 1 2019-03-12 12:14:13 19
--//確實每秒scn增加1,on_disk_rba也是增加每秒1塊.
[20190312]關於增量檢查點的疑問(補充).txt
--//有人問我以前寫一個帖子的問題,關於增量檢查點的問題,鏈接如下:http://blog.itpub.net/267265/viewspace-2136817/
--//實際上我自己看以前寫的帖子一下子有點蒙,主要出現low_rba16=0xffffffff.ffffffff.ffff,為什麽恢復的起點是on_disk_rba16.
--//先簡單說明一下:
--//oracle現在寫臟塊基本采用增量檢查點,即使日誌切換,實際上執行也是增量檢查點,除非執行alter system checkpoint,或者
--//shutdown immediate(normal)正常關閉數據庫,如果異常關閉數據庫,啟動時執行崩潰恢復(crash recovery),恢復起點從low_rba.
1.環境:
SCOTT@book> @ ver1
PORT_STRING VERSION BANNER
------------------- -------------- ----------------------------------------------------------------------------
x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
--//寫一個腳本check.sql,以前寫的太復雜,簡單一點:
--// x$kcccp 記錄增量檢查點
$ cat check.sql
column "full checkpoint_rba" format a21
column low_rba format a20
column low_rba16 format a20
column on_disk_rba format a20
column on_disk_rba16 format a20
column rtckp_rba format a20
column diff_date format 9999999.99
rem column CPOSD_ono_disk_rba_scn format 99999999999999999999999999999999
column cpodt_on_disk_rba heading "檢查點隊列|on disk rba|時間戳|CPODT"
column cpods heading "檢查點隊列|on disk rba scn|CPODS"
column cphbt heading "檢查點心跳|CPHBT"
column current_sysdate heading "當前時間|SYSDATE"
set num 12
SELECT b.cplrba_seq || ‘.‘ || b.cplrba_bno || ‘.‘ || b.cplrba_bof "low_rba"
,b.cpodr_seq || ‘.‘ || b.cpodr_bno || ‘.‘ || b.cpodr_bof "on_disk_rba"
,b.CPODS "on_disk_rba_scn(CPODS)"
,TO_DATE (b.CPODT, ‘MM-DD-YYYY HH24:MI:SS‘) "on_disk_rba_time(CPODT)"
,a.rtckp_rba_seq || ‘.‘ || a.rtckp_rba_bno || ‘.‘ || a.rtckp_rba_bof
"full checkpoint_rba"
,a.rtckp_scn "full_checkpoint(rtckp_scn)"
,TO_DATE (a.rtckp_tim, ‘MM-DD-YYYY HH24:MI:SS‘)
"full_checkpoint_time_rtckp_tim"
,b.CPODS - a.rtckp_scn "diff_scn(on_disk_rdb-ch_scn)"
,a.rtcln "current_group"
,sysdate current_sysdate
,CPDRT
FROM x$kccrt a, x$kcccp b
WHERE a.rtnum = b.cptno AND A.INST_ID = b.inst_id;
2.測試:
SYS@book> shutdown abort ;
ORACLE instance shut down.
SYS@book> startup mount
ORACLE instance started.
Total System Global Area 643084288 bytes
Fixed Size 2255872 bytes
Variable Size 205521920 bytes
Database Buffers 427819008 bytes
Redo Buffers 7487488 bytes
Database mounted.
SYS@book> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /u01/app/oracle/archivelog/book/
Oldest online log sequence 787
Next log sequence to archive 789
Current log sequence 789
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
----------- ----------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
789.5775.0 789.5955.0 13278979623 2019-03-12 11:20:53 789.1890.16 13278977341 2019-03-12 10:52:50 2282 2 2019-03-12 11:21:42 12
--//看看日誌應用的起點是否從low_rba開始.
SYS@book> alter database open ;
Database altered.
--//查看alert.log日誌:
Beginning crash recovery of 1 threads
parallel recovery started with 23 processes
Started redo scan
Completed redo scan
read 90 KB redo, 12 data blocks need recovery
Started redo application at
Thread 1: logseq 789, block 5775
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>起點對應low_rba=789.5775.0
Recovery of Online Redo Log: Thread 1 Group 2 Seq 789 Reading mem 0
Mem# 0: /mnt/ramdisk/book/redo02.log
Completed redo application of 0.00MB
Completed crash recovery at
Thread 1: logseq 789, block 5956, scn 13278999624
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>結束對應on_disk_rba=789.5955.0加1個塊(512字節redo),scn號對應on_disk_rba_scn+1.
12 data blocks read, 12 data blocks written, 90 redo k-bytes read
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--//5955-5775 = 180,應用日誌180塊,日誌文件每塊512字節.
--//180*512/1024 = 90k,這些正好對上.
Tue Mar 12 11:23:26 2019
LGWR: STARTING ARCH PROCESSES
Tue Mar 12 11:23:26 2019
ARC0 started with pid=45, OS id=56804
ARC0: Archival started
LGWR: STARTING ARCH PROCESSES COMPLETE
ARC0: STARTING ARCH PROCESSES
Thread 1 advanced to log sequence 790 (thread open)
Thread 1 opened at log sequence 790
--//日誌切換使用新日誌.
Current log# 3 seq# 790 mem# 0: /mnt/ramdisk/book/redo03.log
Successful open of redo thread 1
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Tue Mar 12 11:23:27 2019
SMON: enabling cache recovery
--//也就是異常關閉後,crash recovery的起點從low_rba到on_disk_rba,完成後scn號+1,日誌塊號加1.日誌切換使用新日誌.
3.如果low_rba16=0xffffffff.ffffffff.ffff呢?
SYS@book> alter system checkpoint ;
System altered.
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 790.659.0 13279000486 2019-03-12 11:32:34 790.658.16 13279000485 2019-03-12 11:32:33 1 3 2019-03-12 11:32:35 0
5.65535
--//等一會執行:
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 790.678.0 13279000505 2019-03-12 11:32:53 790.658.16 13279000485 2019-03-12 11:32:33 20 3 2019-03-12 11:32:54 0
5.65535
--//你可以發現alter system checkpoint 後,如果沒有事務low_rba16=0xffffffff.ffffffff.ffff,而on_disk_rba一直在增加.而CPDRT=0.
--//似乎11g不知道為什麽在"空轉"(沒有事務產生的情況下)的情況,日誌也在不斷增加,不知道為什麽?
SYS@book> shutdown abort ;
ORACLE instance shut down.
SYS@book> startup mount
ORACLE instance started.
Total System Global Area 643084288 bytes
Fixed Size 2255872 bytes
Variable Size 205521920 bytes
Database Buffers 427819008 bytes
Redo Buffers 7487488 bytes
Database mounted.
SYS@book> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 790.705.0 13279000532 2019-03-12 11:33:20 790.658.16 13279000485 2019-03-12 11:32:33 47 3 2019-03-12 11:36:09 0
5.65535
--//可以發現這個時候low_rba16=0xffffffff.ffffffff.ffff,這個時候恢復的起點從那裏開始,實際上從on_disk_rba開始,或者講根本沒
--//有恢復,CPDRT=0也是佐證,雖然當時on_disk_rba還在不斷增加.
SYS@book> alter database open ;
Database altered.
--//查看alert.log:
Beginning crash recovery of 1 threads
parallel recovery started with 23 processes
Started redo scan
Completed redo scan
read 0 KB redo, 0 data blocks need recovery
Started redo application at
Thread 1: logseq 790, block 705, scn 13279000532
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>起點對應on_disk_rba=790.705.0
Recovery of Online Redo Log: Thread 1 Group 3 Seq 790 Reading mem 0
Mem# 0: /mnt/ramdisk/book/redo03.log
Completed redo application of 0.00MB
Completed crash recovery at
Thread 1: logseq 790, block 706, scn 13279020533
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>結束對應on_disk_rba=790.705.0加1個塊(512字節redo),scn號對應on_disk_rba_scn+1.
0 data blocks read, 0 data blocks written, 0 redo k-bytes read
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=> 日誌應用0K.
Tue Mar 12 11:39:33 2019
LGWR: STARTING ARCH PROCESSES
Tue Mar 12 11:39:33 2019
ARC0 started with pid=45, OS id=56980
ARC0: Archival started
LGWR: STARTING ARCH PROCESSES COMPLETE
ARC0: STARTING ARCH PROCESSES
Thread 1 advanced to log sequence 791 (thread open)
Thread 1 opened at log sequence 791
--//日誌切換使用新日誌.
Current log# 1 seq# 791 mem# 0: /mnt/ramdisk/book/redo01.log
Successful open of redo thread 1
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Tue Mar 12 11:39:34 2019
SMON: enabling cache recovery
4.我在原鏈接寫一個腳本:
SCOTT@book> create table t1 as select * from all_objects ;
Table created.
$ cat a.sql
alter system checkpoint;
alter system checkpoint;
alter system checkpoint;
@ check
update scott.t1 set object_name=object_name where rownum=1 ;
commit;
host sleep 3
@ check
SYS@book> @ a.sql
System altered.
System altered.
System altered.
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 791.21362.0 13279021797 2019-03-12 11:52:59 791.21362.16 13279021800 2019-03-12 11:53:00 -3 1 2019-03-12 11:53:01 0
5.65535
1 row updated.
Commit complete.
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.21363.0 791.21366.0 13279021805 2019-03-12 11:53:02 791.21362.16 13279021800 2019-03-12 11:53:00 5 1 2019-03-12 11:53:04 3
--//註意看發生事務前後的low_rba,on_disk_rba.不好描述,自己看.^_^.
--//一旦有事務產生,你可以發現low_rba不再是4294967295.4294967295.65535.
--//很奇怪不知道為什麽11g下在沒有事務的情況下會"空轉",這樣11g的日誌即使是很空閑的數據庫日誌增加也會比10g大.
5.看看10g的情況:
[email protected]:1521/test> @ ver1
PORT_STRING VERSION BANNER
------------------------------ -------------- ----------------------------------------------------------------
x86_64/Linux 2.4.xx 10.2.0.4.0 Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
[email protected]:1521/test> alter system checkpoint ;
System altered.
[email protected]:1521/test> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 1497.42866.0 14987614992 2019-03-12 11:55:37 1497.42866.16 14987615031 2019-03-12 11:57:34 -39 3 2019-03-12 11:57:35 0
5.65535
[email protected]:1521/test> @ check
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
4294967295.429496729 1497.42866.0 14987614992 2019-03-12 11:55:37 1497.42866.16 14987615031 2019-03-12 11:57:34 -39 3 2019-03-12 11:58:29 0
5.65535
--//註意看執行時間2019-03-12 11:57:35 -2019-03-12 11:58:29 之間,沒有任何事務產生,on_disk_rba根本不變化.這樣10g日誌產生量
--//明顯比11g小.
6.我改上面的腳本check.sql:
--//最後加入host sleep 1.執行如下:
$ rlsql -s -l sys/oracle as sysdba <<EOF
> $(seq 100| xargs -I{} cat /home/oracle/sqllaji/check.sql)
> EOF
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24711.0 13279023352 2019-03-12 12:11:39 791.21362.16 13279021800 2019-03-12 11:53:00 1552 1 2019-03-12 12:11:41 8
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24712.0 13279023353 2019-03-12 12:11:40 791.21362.16 13279021800 2019-03-12 11:53:00 1553 1 2019-03-12 12:11:42 8
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24713.0 13279023354 2019-03-12 12:11:41 791.21362.16 13279021800 2019-03-12 11:53:00 1554 1 2019-03-12 12:11:43 8
--//在沒有事務的情況下.每秒scn增加1,日誌塊增加1,是否更我訪問這些內存"表"有關,換1個方式測試,取消check.sql後面的host sleep 1,建立腳本b.sql:
$ cat b.sql
@ check.sql
host sleep 30
@ check.sql
SYS@book> @ b.sql
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24852.0 13279023481 2019-03-12 12:13:41 791.21362.16 13279021800 2019-03-12 11:53:00 1681 1 2019-03-12 12:13:43 19
檢查點隊列
當前時間 臟塊數量
low_rba on_disk_rba on_disk_rba_scn( on_disk_rba_time(CP full checkpoint_rba full_checkpoint( full_checkpoint_tim diff_scn(on_disk_rdb-ch_scn) current_group SYSDATE CPDRT
-------------------- -------------------- ---------------- ------------------- --------------------- ---------------- ------------------- ---------------------------- ------------- ------------------- ------------
791.24582.0 791.24882.0 13279023511 2019-03-12 12:14:11 791.21362.16 13279021800 2019-03-12 11:53:00 1711 1 2019-03-12 12:14:13 19
--//確實每秒scn增加1,on_disk_rba也是增加每秒1塊.
[20190312]關於增量檢查點的疑問(補充).txt