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自我调整检查点的参数约束

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?)


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无觅

By eygle on 2008-07-28 15:14 | Comments (5) | Oracle12c/11g | 1987 |

5 Comments

SelfTune Chechpoint
小纰漏:Chechpoint->Checkpoint

_selftune_checkpoint_write_pct 百分比 3%_disable_selftune_checkpointing 布尔值 FALSE
_selftune_checkpointing_lag 行数 300行

猜的:)

_selftune_checkpointing_lag的单位应该是seconds,缺省300秒

Seconds比较靠谱:)

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


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