[openstack-dev] [Glance] Replacing Glance DB code to Oslo DB code.

Johannes Erdfelt johannes at erdfelt.com
Tue Aug 20 15:16:54 UTC 2013

On Tue, Aug 20, 2013, Flavio Percoco <flavio at redhat.com> wrote:
> There are a couple of things that would worry me about an hypothetic
> support for NoSQL but I guess one that I'd consider very critical is
> migrations. Some could argue asking whether we'd really need them or
> not  - when talking about NoSQL databases - but we do. Using a
> schemaless database wouldn't mean we don't have a schema. Migrations
> are not trivial for some NoSQL databases, plus, this would mean
> drivers, most probably, would have to have their own implementation.

Migrations aren't always about the schema. Take migrations 015 and 017
in glance for instance. They migrate data by fixing the URI and making
sure it's quoted correctly. The schema doesn't change, but the data

This shares many of the same practical problems that schema migrations
have and would apply to NoSQL databases.


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