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Question and Answer

Connor McDonald

Thanks for the question, Vinay.

Asked: August 01, 2025 - 12:45 pm UTC

Last updated: August 06, 2025 - 3:02 am UTC

Version: 19.25.0.0

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You Asked

Hi,

I have a table "XYZ", which needs to be accessed by application in active-active configuration over RAC(19C) in both Primary and Secondary sites. But condition is, connection should hit Primary first. In case Primary has any issues, it needs to be connected on DR site, so DB is always available for connections to table "XYZ". Instead of forming GG with bidirectional, I am thinking of using ADG's DML redirection feature. Could you please shed some light on it?

and Connor said...

OK, there's a lot going there in this question.

active-active configuration over RAC(19C) in both Primary and Secondary sites

Does this mean RAC *across* the sites? Or does it mean RAC at *each* site?

If its the former, then the table will always be available as long as one node is up.
If its the latter, then is the secondary a DataGuard standby?

Can you please clarify the actual setup you have, and I'm sure we can advise you further, but ADG DML is solely about redirecting low-volumes of transactional statements from a read-only standby back to the primary for processing.

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Comments

Vinay, August 04, 2025 - 6:33 am UTC

Thanks to attend it.

Yeh, it is RAC on both sites, Primary(2 nodes RAC), Standby(2 nodes, RAC).

I want to update same database on Primary and Standby, same table.
I will be hitting queries on Primary site only, but in case when Primary, due to uncertain reasons down, It should be able to update same table automatically without changing any thing at Standby site.
Connor McDonald
August 05, 2025 - 2:49 am UTC

If your primary is down, then your standby should now be active no?

That is the role of the standby - to *become* the primary if the primary is lost

DB Architect

A reader, August 05, 2025 - 5:16 am UTC

Hi,

I am trying to configure Primary DB as active only, but in case there is some issue, and for some time Primary is not accessible, application should be able to update in Active Dataguard.
Once Primary becomes available again user would start connecting and updating in Primary again and not in Dataguard.


Connor McDonald
August 06, 2025 - 3:02 am UTC

If your primary is not accessible, there is no way that any ins/upd/del DML against the Active DataGuard node is possible.

ADG

A reader, August 05, 2025 - 6:16 am UTC 


Hello,

"Once Primary becomes available again user would start connecting and updating in Primary again and not in Dataguard."

Unless you failover to standby, it is still in RO mode in which case "updating" the data will not work even if the application can connect to it.

Either you have either failover automatically or manually but essentially the standby will have to become the new Primary and allow RW transactions.

That is essentially what Connor is trying to convey.

Connor McDonald
August 06, 2025 - 3:01 am UTC

yup
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