July 28, 2008
自我调整检查点的参数约束
作者:eygle
出处:http://blog.eygle.com
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？）
Posted by eygle at 3:14 PM | Comments (5)