Re: Upgrade DB with no downtime

A pair of databases with the application's tables replicated using multimaster replication would allow what the poster is asking.

8i, 9i or 10g databases are able to engage in multimaster replication with each other, so I think this would be an acceptable answer.

This would require an initial single brief (well scripted) downtime to rename and open a standby in sync with the primary, and enable multimaster replication on the appropriate application tables. From then on, users could be switched back and forth between them using tnsnames, and the upgrades could be perforned on whichever database the users are not using.

--
Jeremiah Wilton
http://www.speakeasy.net/~jwilton

On Thu, 27 May 2004, Jared Still wrote:



> On Thu, 2004-05-27 at 05:02, Ivan Chow wrote:

> > The database needs to be available in read-write mode when we do the upgrade

> > from 8i to 9i or 9i to 10G. Hardware is not an issue as long as we can

> > achieve zero downtime during the upgrade. Not sure how we can achieve that.

> > Anyone has any experience or suggestions?

>

> When you consider that the database being migrated must be in

> 'startup migrate' mode, and that *many* changes will be made

> to the data dictionary, it would not seem possible to do

> what you are asking.

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