Saturday , May 28 2022

Standby Max Data Delay

In today’s article, we will talk about Standby Max Data Delay.

While some of the reporting users who make inquiries from Active Data Guard expect the retrieved data to be the same as the Production at that moment, others do not care if LAG has been formed for a few seconds.

The time until this LAG in between is not important to them. But they do not want the result of such a query for higher. For such cases, ORACLE has created the STANDBY_MAX_DATA_DELAY parameter, which will be valid at the session level for the Standby side. This parameter takes seconds.

Use of:

Let’s test it.

1. We check whether the Data Guard is working properly on the Primary and Standby sides.

[Primary -1] [Primary -1] [Primary -2] [Primary -1] [Standby-1] [Standby-2] 2. We set the relevant parameter at session level to a user other than SYS.

[Standby -1] 3.We stop the RECOVER process so that LAG can occur.

[Standby -1] 4.We do a delete operation on the primary side.

[Primary-1] 5. On the standby side, we make a query to see if the delete operation has taken place on the relevant table.

[Standby-1] 6.We learn the duration of the LAG to see that the system is working correctly.

[Standby-1] 7. Since the user’s session is broken, we reconnect and query.

[Standby-1] 8.We initiate the RECOVER operation and query.

[Standby-1] 9.Everything is Ok.

10. If I want, I can make this process permanent with an AFTER LOGON TRIGGER.

[Primary-1] 11. RECOVER is stopped so that LAG can occur.

[Standby-1] 12. The user tries to login.

[Standby-1]

13. We check if other users have problems.

[Standby-1]  

Onur ARDAHANLI
Author: Onur ARDAHANLI

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