1、
备库sqlplus>select value from v$dataguard_stats where name='apply lag'

2、
备库sqlplus>select ceil((sysdate-next_time)*24*60) "M" from v$archived_log where applied='YES' AND SEQUENCE#=(SELECT MAX(SEQUENCE#)  FROM V$ARCHIVED_LOG WHERE applied='YES');

文章题目：dataguard主备延迟多长时间的2种查询方法
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