第六章重做缓冲区调整

Click to edit Master title style,First Level,Second Level,-,*,重做日志缓冲区的调整,本章目的,学完本章之后，我们可以掌握以下的内容:,判断进程是否在等待重做日志缓冲区,给重做日志缓冲区一个适当的大小,重做日志缓冲区,Database buffer,cache,Redo,log,buffer,Shared pool,Library cache,Data dictionary cache,User Global Area,SQL UPDATE,emp,2 SET,sal,=,sal,*1.1,3 WHERE,empno,=7369;,Serverprocess,LGWR,Control files,Data files,Redo logfiles,ARC,n,Archivedlog files,重做日志缓冲区的大小,LOG_BUFFER,参数,默认值:不同的操作系统平台不一样,重做日志缓冲区的调整,SQL UPDATE,emp,2 SET,sal,=,sal,*1.1,3 WHERE,empno,=7369;,LGWR,Redo logfiles,ARCH,Archivedlog files,SQL DELETE FROM s_,emp,2 WHERE,empno,=7400;,Serverprocess,Serverprocess,调整重做日志缓冲区所用到的视图,V$SESSION_WAIT,Log Buffer Space event,Redo log buffer,V$SYSSTAT,Redo Buffer Allocation Retries statistic,LOG_BUFFER,LOG_CHECKPOINT_INTERVALLOG_CHECKPOINT_TIMEOUT,指导方针,Redo Buffer Allocation Retries,的值应该接近;数量应该少于,Redo Entries,的 1%.,SQL SELECT name,value,2 FROM v$,sysstat,3 WHERE name IN(redo buffer allocation retries,4 redo entries);,应该没有重做日志缓冲区空间的等待事件.,SQL SELECT,sid,event,seconds_in_wait,state,2 FROM v$session_wait,3 WHERE event=log buffer space;,总结,在本章，我们学会:,对重做日志缓冲区进行调整,