Dataguard ( Standby ) Monitoring Lag Command and Scripts | Oracle DBA Scripts All in One -2

Hi,

I will share all Oracle DBA Scripts related Dataguard in this post.

 

Oracle DBA ( Database Administrator ) needs useful scripts to monitor, analyze and check Oracle database for routine database operations and monitoring.

 

 

Before Oracle DBA Scripts, If you don’t know Oracle database and want to learn, click following link to start learning Oracle database with this tutorial.

 

Oracle Tutorial | Oracle Database Tutorials for Beginners ( Junior Oracle DBA )

 

 

 

Dataguard Monitoring Scripts – v$dataguard_stats

 

Your dataguard is running but is there any lag ? You can learn below script.

set lines 1000
select name,value from v$dataguard_stats;




Standby ( Dataguard ) Lag

If you want to know which archive sequence number comes from the Primary database lastly and which is last applied in Standby, you can learn the following script.

SELECT ARCH.THREAD# "Thread", ARCH.SEQUENCE# "Last in Sequence", APPL.SEQUENCE# "Last Applied Sequence", (ARCH.SEQUENCE# - APPL.SEQUENCE#) "Difference"
FROM
(SELECT THREAD# ,SEQUENCE# FROM V$ARCHIVED_LOG WHERE (THREAD#,FIRST_TIME ) IN (SELECT THREAD#,MAX(FIRST_TIME) FROM V$ARCHIVED_LOG GROUP BY THREAD#)) ARCH,
(SELECT THREAD# ,SEQUENCE# FROM V$LOG_HISTORY WHERE (THREAD#,FIRST_TIME ) IN (SELECT THREAD#,MAX(FIRST_TIME) FROM V$LOG_HISTORY GROUP BY THREAD#)) APPL
WHERE
ARCH.THREAD# = APPL.THREAD#
ORDER BY 1;





Dataguard Stop / Start

To stop dataguard you can use following query. When dataguard is stopped, MRP ( Media Recovery Process ) won’t run.

alter database recover managed standby database cancel;


To start dataguard you can use following query. When dataguard is started, MRP ( Media Recovery Process ) will run.

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;



If you don’t want any lag you should start dataguard with using logfile option. You should add standby logs to the standby database in this case.

 

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;



If you want to learn which of database is Standby and which of database is Primary, you can execute below query.

 

SELECT database_role, open_mode FROM v$database;



Dataguard ( Standby ) Processes

You can display the status of background processes in a standby database with below script.

select process, client_process,thread#,sequence#,status from v$managed_standby;

You can just want to see MRP process status then you can execute below script.

select process, client_process,thread#,sequence#,status from v$managed_standby where process like '%MRP%';

 

 

What is the MRP process waiting for status ? You can check with below script.

select a.event, a.wait_time, a.seconds_in_wait from gv$session_wait a, gv$session b where a.sid=b.sid and 
b.sid=(select SID from v$session where PADDR=(select PADDR from v$bgprocess where NAME='MRP0'));


To see the status of the switchover and the role of database which is in Standby or Primary state, execute following script.

select switchover_status,database_role from v$database;


To see archive gap in dataguard, execute following script.

SELECT THREAD#, LOW_SEQUENCE#, HIGH_SEQUENCE# FROM V$ARCHIVE_GAP;



Below script provides information about approximate completion time of the recovery process

select to_char(start_time,'DD-MON-RR HH24:MI:SS') start_time,item,round(sofar/1024,2) "MB/Sec" from v$recovery_progress 
where (item='Active Apply Rate' or item='Average Apply Rate');


Dataguard Parameters

To see all parameters of Oracle dataguard, you can execute following query.

 

set linesize 500 pages 0
col value for a80
col name for a50

select name, value from v$parameter
where name in ('db_name','db_unique_name','log_archive_config',    
'log_archive_dest_1','log_archive_dest_2','log_archive_dest_3',
               'log_archive_dest_state_1','log_archive_dest_state_2','log_archive_dest_state_3', 'remote_login_passwordfile',
               'log_archive_format','log_archive_max_processes','fal_server','fal_client','db_file_name_convert',
              'log_file_name_convert', 'standby_file_management') order by 1;




To see applied archivelogs in dataguard, execute following script.

 select thread#,sequence#,first_time,next_time,applied from gv$archived_log where applied='YES';



Below script provides information about max sequence of dataguard

select thread#,max(sequence#) from gv$archived_log group by thread#;



 

 

You can access the First Oracle DBA scripts related to RAC with following link.

Useful Oracle RAC (Cluster Command) Scripts | Oracle DBA Scripts All in One -1

 

 

 

 

Do you want to learn Oracle Database Performance Tuning detailed, then read the following articles.

Performance Tuning and SQL Tuning Tutorial in the Oracle Database

 

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About Mehmet Salih Deveci

I am Founder of SysDBASoft IT and IT Tutorial and Certified Expert about Oracle & SQL Server database, Goldengate, Exadata Machine, Oracle Database Appliance administrator with 10+years experience.I have OCA, OCP, OCE RAC Expert Certificates I have worked 100+ Banking, Insurance, Finance, Telco and etc. clients as a Consultant, Insource or Outsource.I have done 200+ Operations in this clients such as Exadata Installation & PoC & Migration & Upgrade, Oracle & SQL Server Database Upgrade, Oracle RAC Installation, SQL Server AlwaysOn Installation, Database Migration, Disaster Recovery, Backup Restore, Performance Tuning, Periodic Healthchecks.I have done 2000+ Table replication with Goldengate or SQL Server Replication tool for DWH Databases in many clients.If you need Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS Consultancy and Training you can send my email adress mehmetsalih.deveci@outlook.com.-                                                                                                                                                                                                                                                 -Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  mehmetsalih.deveci@outlook.com a mail atabilirsiniz.

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3 comments

  1. I have heard of a command as this

    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE; — this would open the DG Database in Read-Write mode.

    Could you please clarify more on the below command ?
    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;

    • Hi,

      First command is not open database read write Mode. Second Command is start dataguard mrp (media Recovery process immediately ) process, thus lag will decrease and dataguard will be syncronized

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