Upgrades with no downtime
- From: Johan Eriksson <valpis@xxxxxxxxx>
- To: Oracle Discussion List <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 27 Oct 2009 14:44:36 +0100
Hi
We had an discussion about how we could solve the problem with no
downtime during upgrades and I want to know if anyone of you have had
an similiar problem before and if you could help me with some advice
on how to solve this.
Our current setup is we have some application servers with most of the
logic, and in the database we have some pl/sql logic and the data.
The problem we have is when we have an deployment of code or changes
in the database we also need to take down the system since we can't
make changes in the tables for example.
My first thought is that we should split the logic and data in the
database into different schemas, and let the logicschema has views
that points to the physical storage of the data in another schema. By
doing this we could have several schemas with logic( and views) in the
database and we could make changes on the tables without affecting the
logic. (We rarely deletes any columns and if we do we have to face
downtime). And by doing this we could make the changes to the tables
and create a new schema with logic and then this is done we shift the
application servers to the new schema, and if we also have changes in
the code in the application servers we take down couple of the
application servers and commit the changes, bring them up and make the
run against the new schema and then we are done we take the rest of
the application servers. We will not have perfectly smooth upgrades by
doing this since we will loose connections when we switch, but we
won't have an hour long downtime.
Don't like the idea on using views like this, this is only my first
thought about it.
I don't think we are the first ones to hit this problem, but how has
others solved them? I look forward to your suggestions and comments
about this.
/johan
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