#### redo log ####
*******************************************************************
archive log list;--??榈�?
alter system archive log start;--启动自动存档
alter system switch logfile;--强行进行一次日志switch
alter system checkpoint;--强制进行一次checkpoint
alter tablspace users begin backup;
alter tablespace tablespace_name offline;
/*checkpoint 同步频率参数FAST_START_MTTR_TARGET,同步频率越高，系统恢复所需时间越短*/
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************************************************
show parameter fast;
show parameter log_checkpoint;
************************************************
/*??*/
alter database add logfile group 3 ('/$ORACLE_HOME/oracle/ora_log_file6.rdo' size 10M);
或者：
SQL>alter database add logfile group 4 '/opt/oracle/oradata/cicro/redo04.log' size 100m; /*加入一个日志组*/
************************************************
/*???*/
alter database add logfile member '/$ORACLE_HOME/oracle/ora_log_file6.rdo' to group 3;
************************************************
/*??:??椴�???椴�??榈�?椴�?*/
alter database drop logfile group 3;
************************************************
/*??械???????*/
alter databse drop logfile member '$ORACLE_HOME/oracle/ora_log_file6.rdo';
*************************************************
/*?*/
alter database clear logfile '$ORACLE_HOME/oracle/ora_log_file6.rdo';
alter database clear logfile group 3;
*************************************************
/*?榈�?*/
alter database clear unarchived logfile group 3;
*************************************************
/*重命名重做日志文件*/
alter database rename file '$ORACLE_HOME/oracle/ora_log_file6.rdo' to '$ORACLE_HOME/oracle/ora_log_file6a.rdo';
/*改变重做日值的位置*/
sql> alter database rename file 'c:/oracle/oradata/oradb/redo01.log'
to 'c:/oracle/oradata/redo01.log';
**************************************************
show parameter db_create;
alter system set db_create_online_log_dest_1='path_name';
select * from v$log;
select * from v$logfile;
***************************************************
/*数据库归档模式到非归档模式的互换,要启动到mount状态下才能改变;startup mount;然后再打开数据库.*/
alter database noarchivelog/archivelog;
alter system achive log start/stop;---启动或者停止自动归档，但如果数据库重起后，该语句修改的结果就失效了。
alter system archive all;?榈�??
select * from v$archived_log;
show parameter log_archive;
****************************************************
10. using logminer analyzing redo logfiles
a. in the init.ora specify utl_file_dir = ' '
b. sql> execute dbms_logmnr_d.build('oradb.ora','c:\oracle\oradb\log');
c.sql>execute
dbms_logmnr_add_logfile('c:\oracle\oradata\oradb\redo01.log',
dbms_logmnr.new);
d.sql>execute dbms_logmnr.add_logfile('c:\oracle\oradata\oradb\redo02.log',
