标签：system table 2.4 sql disco home 接收 cancel member
启动实时应用的优势在于，REDO数据不需要等待归档完成，接收到即可被应用，这样执行角色切换时，操作能够执行得更快，因为日志是被即时应用的。
要启动实时应用也简单，前提是Standby数据库端配置了Standby Redologs。
物理Standby要启用实时应用，要在启动REDO应用的语句后附加USING CURRENT LOGFIE子句，例如：
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE ;
首先查询当前redo log的大小、位置；Standby redo的大小要和redo 的一致
primary>col status format ‘a10‘ primary>select group#,thread#,archived,status, bytes/1024/1024 from v$log; GROUP# THREAD# ARCHIVED STATUS BYTES/1024/1024 ---------- ---------- --------- ---------- --------------- 1 1 YES INACTIVE 50 2 1 NO CURRENT 50 3 1 YES INACTIVE 50 primary>col member format ‘a35‘; primary>select group#,type, member from v$logfile; GROUP# TYPE MEMBER ---------- --------------------- ----------------------------------- 1 ONLINE /u01/app/oradata/ora234/redo01.log 2 ONLINE /u01/app/oradata/ora234/redo02.log 3 ONLINE /u01/app/oradata/ora234/redo03.log
添加standby redo 操作；主库/备库都操作；
主库操作原因；当发生故障；主备库发生切换；减少切换过程操作
主库操作 primary> ALTER DATABASE ADD STANDBY LOGFILE GROUP 4 (‘/home/oracle/oradata/redolog/std_redo04.log‘) size 50M; Database altered. primary> ALTER DATABASE ADD STANDBY LOGFILE GROUP 5 (‘/home/oracle/oradata/redolog/std_redo05.log‘) size 50M; Database altered. primary> ALTER DATABASE ADD STANDBY LOGFILE GROUP 6 (‘/home/oracle/oradata/redolog/std_redo06.log‘) size 50M; Database altered. primary> ALTER DATABASE ADD STANDBY LOGFILE GROUP 7 (‘/home/oracle/oradata/redolog/std_redo07.log‘) size 50M; Database altered. 备库操作 standby> ALTER DATABASE ADD STANDBY LOGFILE GROUP 4 (‘/home/oracle/oradata/redolog/std_redo04.log‘) size 50M; Database altered. standby> ALTER DATABASE ADD STANDBY LOGFILE GROUP 5 (‘/home/oracle/oradata/redolog/std_redo05.log‘) size 50M; Database altered. standby> ALTER DATABASE ADD STANDBY LOGFILE GROUP 6 (‘/home/oracle/oradata/redolog/std_redo06.log‘) size 50M; Database altered. standby> ALTER DATABASE ADD STANDBY LOGFILE GROUP 7 (‘/home/oracle/oradata/redolog/std_redo07.log‘) size 50M; Database altered.
启动实时应用日志；需采用lgwr模式；即应用redolog。不再是archivelog
primary>alter system set LOG_ARCHIVE_DEST_2=‘SERVICE=tns_standby LGWR VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_standby‘ ; System altered. standby>alter system set log_archive_dest_2=‘SERVICE=tns_primary LGWR VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=db_primary‘; System altered.
StandBy>alter database recover managed standby database using current logfile disconnect from session; 取消实时应用：alter database recover managed standby database cancel;
primary>truncate table t; Table truncated. primary>insert into t values (1000); 1 row created. primary>commit; Commit complete. standby>select * from t; no rows selected standby>select * from t; ID ---------- 1000
标签：system table 2.4 sql disco home 接收 cancel member
原文地址：http://www.cnblogs.com/lottu/p/7058774.html
