[20190312]关于增量检查点的疑问(补充).txt
[20190312]关于增量检查点的疑问(补充).txt
--//有人问我以前写一个帖子的问题,关于增量检查点的问题,链接如下:http://blog.itpub.net/267265/viewspace-2136817/
--//实际上我自己看以前写的帖子一下子有点蒙,主要出现low_rba16=0xffffffff.ffffffff.ffff,为什么恢复的起点是on_disk_rba16.
--//先简单说明一下:
--//oracle现在写脏块基本采用增量检查点,即使日志切换,实际上执行也是增量检查点,除非执行alter system checkpoint,或者
--//shutdown immediate(normal)正常关闭数据库,如果异常关闭数据库,启动时执行崩溃恢复(crash recovery),恢复起点从low_rba.
--//先验证这样的情况:
1.环境:
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
--//写一个脚本check.sql,以前写的太复杂,简单一点:
--// x$kccrt 记录全检查点
--// x$kcccp 记录增量检查点
$ 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 cpdrt heading "检查点队列|脏块数量|CPDRT"
column cpodt_on_disk_rba heading "检查点队列|on disk rba|时间戳|CPODT"
column cpods heading "检查点队列|on disk rba scn|CPODS"
column cphbt heading "检查点心跳|CPHBT"
column current_sysdate heading "当前时间|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.测试:
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
检查点队列
当前时间 脏块数量
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
--//看看日志应用的起点是否从low_rba开始.
SYS@book> alter database open ;
Database altered.
--//查看alert.log日志:
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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>起点对应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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>结束对应on_disk_rba=789.5955.0加1个块(512字节redo),scn号对应on_disk_rba_scn+1.
12 data blocks read, 12 data blocks written, 90 redo k-bytes read
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--//5955-5775 = 180,应用日志180块,日志文件每块512字节.
--//180*512/1024 = 90k,这些正好对上.
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
--//日志切换使用新日志.
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
--//也就是异常关闭后,crash recovery的起点从low_rba到on_disk_rba,完成后scn号+1,日志块号加1.日志切换使用新日志.
3.如果low_rba16=0xffffffff.ffffffff.ffff呢?
SYS@book> alter system checkpoint ;
System altered.
SYS@book> @ check
检查点队列
当前时间 脏块数量
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
--//等一会执行:
SYS@book> @ check
检查点队列
当前时间 脏块数量
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
--//你可以发现alter system checkpoint 后,如果没有事务low_rba16=0xffffffff.ffffffff.ffff,而on_disk_rba一直在增加.而CPDRT=0.
--//似乎11g不知道为什么在"空转"(没有事务产生的情况下)的情况,日志也在不断增加,不知道为什么?
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
检查点队列
当前时间 脏块数量
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
--//可以发现这个时候low_rba16=0xffffffff.ffffffff.ffff,这个时候恢复的起点从那里开始,实际上从on_disk_rba开始,或者讲根本没
--//有恢复,CPDRT=0也是佐证,虽然当时on_disk_rba还在不断增加.
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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>起点对应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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=>结束对应on_disk_rba=790.705.0加1个块(512字节redo),scn号对应on_disk_rba_scn+1.
0 data blocks read, 0 data blocks written, 0 redo k-bytes read
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=> 日志应用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
--//日志切换使用新日志.
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.我在原链接写一个脚本:
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.
检查点队列
当前时间 脏块数量
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.
检查点队列
当前时间 脏块数量
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
--//注意看发生事务前后的low_rba,on_disk_rba.不好描述,自己看.^_^.
--//一旦有事务产生,你可以发现low_rba不再是4294967295.4294967295.65535.
--//很奇怪不知道为什么11g下在没有事务的情况下会"空转",这样11g的日志即使是很空闲的数据库日志增加也会比10g大.
5.看看10g的情况:
SYS@192.168.100.33:1521/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
SYS@192.168.100.33:1521/test> alter system checkpoint ;
System altered.
SYS@192.168.100.33:1521/test> @ check
检查点队列
当前时间 脏块数量
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
SYS@192.168.100.33:1521/test> @ check
检查点队列
当前时间 脏块数量
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
--//注意看执行时间2019-03-12 11:57:35 -2019-03-12 11:58:29 之间,没有任何事务产生,on_disk_rba根本不变化.这样10g日志产生量
--//明显比11g小.
6.我改上面的脚本check.sql:
--//最后加入host sleep 1.执行如下:
$ rlsql -s -l sys/oracle as sysdba <<EOF
> $(seq 100| xargs -I{} cat /home/oracle/sqllaji/check.sql)
> EOF
检查点队列
当前时间 脏块数量
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
检查点队列
当前时间 脏块数量
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
检查点队列
当前时间 脏块数量
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
--//在没有事务的情况下.每秒scn增加1,日志块增加1,是否更我访问这些内存"表"有关,换1个方式测试,取消check.sql后面的host sleep 1,建立脚本b.sql:
$ cat b.sql
@ check.sql
host sleep 30
@ check.sql
SYS@book> @ b.sql
检查点队列
当前时间 脏块数量
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
检查点队列
当前时间 脏块数量
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
--//确实每秒scn增加1,on_disk_rba也是增加每秒1块.
[20190312]关于增量检查点的疑问(补充).txt的更多相关文章
- oracle检查点队列与增量检查点【转载】
oracle检查点队列与增量检查点 今天是2013-09-04,这几天一直心里安顿不下来,今天还好了,可以自己安静的学习一下oracle,在此记录一下学习笔记.这篇文章我不知道在那转载的,一直都留在我 ...
- OCP知识点讲解 之 检查点队列与增量检查点
原创 http://blog.chinaunix.net/uid-26762723-id-3271558.html 检查点的主要目的是以对数据库的日常操作影响最小的方式刷新脏块.脏块不断的产生,如何将 ...
- [20190510]rman备份的疑问8.txt
[20190510]rman备份的疑问8.txt --//上午测试rman备份多个文件,探究input memory buffer 的问题.--//补充测试5个文件的情况.--//http://blo ...
- [20190423]那个更快的疑问3.txt
[20190423]那个更快的疑问3.txt --//前一阵子,做了11g在单表单条记录唯一索引扫描的测试,摘要如下:--//参考链接:http://blog.itpub.net/267265/vie ...
- [20190312]视图v$datafile字段OFFLINE_CHANGE#, ONLINE_CHANGE#.txt
[20190312]视图v$datafile字段OFFLINE_CHANGE#, ONLINE_CHANGE#.txt --//视图v$datafile存在2个字段OFFLINE_CHANGE#, O ...
- [20190214]11g Query Result Cache RC Latches补充.txt
[20190214]11g Query Result Cache RC Latches补充.txt --//上午测试链接:http://blog.itpub.net/267265/viewspace- ...
- [20180928]ora-01426(补充).txt
[20180928]ora-01426(补充).txt --//链接:http://www.itpub.net/thread-2105458-1-1.html--//做一点点必要的补充: 1.环境:S ...
- [20170604]12c Top Frequency histogram补充.txt
[20170604]12c Top Frequency histogram补充.txt 1.环境:SCOTT@test01p> @ ver1PORT_STRING ...
- [20171107]dbms_shared_pool.pin补充.txt
[20171107]dbms_shared_pool.pin补充.txt --//上午的测试,做一些补充,主要还是一些理解问题. 1.环境:SCOTT@book> @ &r/ver1 P ...
随机推荐
- SHELL脚本--变量(基础)
bash&shell系列文章:http://www.cnblogs.com/f-ck-need-u/p/7048359.html 变量存在于内存中.假设变量str,设置或修改变量属性时,不带$ ...
- haproxy(8):haproxy代理MySQL要考虑的问题
HaProxy系列文章:http://www.cnblogs.com/f-ck-need-u/p/7576137.html haproxy可以通过 TCP协议 来代理MySQL.但是两个问题必须考虑: ...
- #if 与 #ifdef 之间的区别
先来看个例子: #define TARGET_LITTLE_ENDINA 1 #define TARGET_BIG_ENDINA 0 #ifdef TARGET_LITTLE_ENDINA call ...
- [转]从minio中读取文件流进行下载文件
本文转自:https://blog.csdn.net/ZHANGLIZENG/article/details/82892678 一.获取Minio连接 public static String ...
- Webservice开发、引用
一.Webservice开发 1.在解决方案右键添加新建项目,新建空的web应用程序 2.在新建的项目右键添加新建项选择web服务 3.这里就是webservice 里的方法,可以添加自己需要的方法( ...
- EF(EntityFramework)与mysql使用,取数据报错,linq实体映射错误
报错信息:LINQ to Entities does not recognize the method 'System.String ToString()' method, and this meth ...
- c# partial 关键字的使用
C# 2.0 引入了局部类型的概念.局部类型允许我们将一个类.结构或接口分成几个部分,分别实现在几个不同的.cs文件中. 局部类型适用于以下情况: (1) 类型特别大,不宜放在一个文件中实现.(2) ...
- async,await,Task 的一些用法
async,await,Task 的一些用法 private void Form1_Load(object sender, EventArgs e) { Display(); } public asy ...
- MyISAM和InnoDB区别详解
MyISAM是MySQL的默认数据库引擎(5.5版之前),由早期的ISAM(Indexed Sequential Access Method:有索引的顺序访问方法)所改良.虽然性能极佳,但却有一个缺点 ...
- 【Java基础】16、小数的浮点型和定点型
一.简介 1.对于不需要任何准确计算精度的数字可以直接使用浮点型,但是如果需要精确计算的结果,则必须使用定点型(BigDecimal类) 浮点型:float,double 定点型:BigDecimal ...