Online Upgrade

From: Purav Chovatia <>
Date: Tue, 20 Mar 2012 12:06:49 +0530
Message-ID: <>

We have a requirement to apply application patches online i.e. without downtime. Our apps run in active-active mode and hence the app layer is taken care of i.e. while instance-1 of app is being upgraded, the live traffic is handled by instance-2. And once that is done, live traffic is handled by instance-2 and instance-1 is upgraded. However the challenge is to modify the DB objects i.e. SPs, tables, indices, etc.

When I was given this requirement, initially I resisted. But later I thought, may be this looks like a common problem with increasing demand of high availability. So can you pls give me some guidance on how is this requirement handled across the industry? What do you all do? For e.g. if I have to modify a SP, I know that cannot be done while the apps are accessing it. Is there some workaround? May be writing wrappers, etc.?
Similarly for other changes like adding or dropping a column.

I think Edition based Redifinition is a step towards it but a first glance at it made me feel that its very complicated, still maturing, and does not cover all types of changes.

If anybody has some best practices that are being followed can you please share?


Received on Tue Mar 20 2012 - 01:36:49 CDT

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