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自我调整检查点的参数约束
作者：eygle |【转载时请以超链接形式标明文章出处和作者信息及本声明】链接：http://www.eygle.com/archives/2008/07/selftune_checkpoint.html
Oracle10gR2开始引入了自动检查点调整（SelfTune Checkpoint），这个特性可以通过设置FAST_START_MTTR_TARGET为0来启用。
同时Oracle也引入了几个隐含参数用于约束这个特性：
SQL> SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.KSPPDESC PDESC
2 FROM SYS.x$ksppi x, SYS.x$ksppcv y
3 WHERE x.indx = y.indx
4 AND x.ksppinm LIKE '%&par%'
5 /
Enter value for par: selftune
old 4: AND x.ksppinm LIKE '%&par%'
new 4: AND x.ksppinm LIKE '%selftune%'
NAME VALUE PDESC
----------------------------------- ----- -------------------------------------------------------
_selftune_checkpoint_write_pct 3 Percentage of total physical i/os for self-tune ckpt
_disable_selftune_checkpointing FALSE Disable self-tune checkpointing
_selftune_checkpointing_lag 300 Self-tune checkpointing lag the tail of the redo log
（这几个参数的单位不知道是用什么表示？）
历史上的今天...
>> 2007-07-28文章:
>> 2006-07-28文章:
>> 2005-07-28文章:
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By eygle on 2008-07-28 15:14 | Comments (5) | Posted to Oracle10g/11g | Edit |
留言 (5)
SelfTune Chechpoint
小纰漏：Chechpoint->Checkpoint
Posted by: solorez at July 28, 2008 6:22 PM
_selftune_checkpoint_write_pct 百分比 3%_disable_selftune_checkpointing 布尔值 FALSE
_selftune_checkpointing_lag 行数 300行
猜的:)
Posted by: wangliang at July 29, 2008 10:52 AM
_selftune_checkpointing_lag的单位应该是seconds，缺省300秒
Posted by: thomas zhang at July 30, 2008 11:25 AM
Seconds比较靠谱：）
Posted by: eygle at July 30, 2008 1:49 PM
Oracle 11.1.0:
Parameter Name: _selftune_checkpointing_lag
Description: Self-tune checkpointing lag the tail of the redo log
Type: NUMBER Obsoleted: FALSE
Can ALTER SESSION: FALSE Can ALTER SYSTEM: FALSE
Oracle 10.2.0:
Parameter Name: _selftune_checkpointing_lag
Description: Self-tune checkpointing lag the tail of the redo log
Type: NUMBER Obsoleted: FALSE
Can ALTER SESSION: FALSE Can ALTER SYSTEM: FALSE
Posted by: ooo at August 3, 2008 11:15 AM