[openstack-dev] [tc] Active or passive role with our database layer

Sean Dague sean at dague.net
Tue May 23 11:57:01 UTC 2017

On 05/23/2017 07:23 AM, Chris Dent wrote:
>> Some operations have one and only one "right" way to be done. For
>> those operations if we take an 'active' approach, we can implement
>> them once and not make all of our deployers and distributors each
>> implement and run them. However, there is a cost to that. Automatic
>> and prescriptive behavior has a higher dev cost that is proportional
>> to the number of supported architectures. This then implies a need to
>> limit deployer architecture choices.
> That "higher dev cost" is one of my objections to the 'active'
> approach but it is another implication that worries me more. If we
> limit deployer architecture choices at the persistence layer then it
> seems very likely that we will be tempted to build more and more
> power and control into the persistence layer rather than in the
> so-called "business" layer. In my experience this is a recipe for
> ossification. The persistence layer needs to be dumb and
> replaceable.


Do you have an example of an Open Source project that (after it was
widely deployed) replaced their core storage engine for their existing

I do get that when building more targeted things, this might be a value,
but I don't see that as a useful design constraint for OpenStack.


Sean Dague

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