[Openstack-operators] [all] SQL Schema Downgrades: A Good Idea?

Jesse Keating jlk at bluebox.net
Fri Jan 30 19:40:35 UTC 2015

On 1/30/15 11:37 AM, Tim Bell wrote:
> Any ideas how are the online upgrade teams looking to address this ? Not an easy problem to solve.

The direction is additive migrations. Create new columns and tables for 
new place for the data, but support pulling data from old locations as 
well. Once all the consumers/producers can read the new table, 
background data migration starts. Eventually the old tables can be 
dropped, but that can be an admin action later.

Expand / contract is the term being throw around for this.

Of course, each project is tackling it on their own, and I'm mostly 
speaking about Nova.


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