Re: Applying logs to standby in 11g

From: Saibabu Devabhaktuni <saibabu_d_at_yahoo.com>
Date: Wed, 24 Oct 2012 11:21:38 -0700 (PDT)
Message-ID: <1351102898.24151.YahooMailNeo_at_web161304.mail.bf1.yahoo.com>

Yong Huang just sent me a note that the below query doesn't work on the dataguard when it is in the mount mode, he is right below query works only on Active dataguard and when the standby is in read only mode. select
abs(nvl(max(ceil(
(extract(day from replication_lag)*24*60*60)+
(extract(hour from replication_lag)*60*60)+
(extract(minute from replication_lag)*60)+
(extract(second from replication_lag))

)),0)) lag_in_seconds from
(select sysdate-scn_to_timestamp(current_scn) replication_lag from v$database);

You can use below query to get the lag when standby is in mount mode in addition to relying on v$dataguard_stats:

select max(lag_time) lag_time from
(select max(timestamp) lag_time from v$recovery_progress where type='Media Recovery' and item='Last Applied Redo'
union all
select max(checkpoint_time) lag_time from v$datafile where file#=1);

Parameter standby_max_data_delay and current_scn in v$database rely on the recovery progress maintained in v$recovery_progress.

Thanks,
Sai
http://sai-oracle.blogspot.com

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Received on Wed Oct 24 2012 - 20:21:38 CEST