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[placement][ptg] Resource Provider Partitioning


On Tue, 16 Apr 2019, Dan Smith wrote:

>> So, for the sake of making it explicit, what's wrong with:
>>
>> * add a nullable shard column
>> * enable the openstack-shard header I suggested at the last ptg [1]
>> * let deployments start using that, but only if they want to. If
>>   they do all rp writes and queries use it.
>
> This sounds like a trap, so I'm curious... What, um, is left in such a
> feature beyond this? :)

Sorry, no trap intended. I had recalled that you had a preference to
not null and I couldn't remember the reasons.

[snip]

> I'm not crazy opposed to everyone being in the undeclared null shard
> until they need to be in something else. I don't prefer it because:
>
> - I think it will be better tested (and test-able) if it's not optional
> - It's an identifier, and we'd never say "we don't need a non-null row
>   id column until later when we need it"
> - I think that other services that may start reporting to or using
>   placement may just omit that part in early development

For completeness, your preference would be something more like the
way we do incomplete project and user for allocations that pre-dated
consumers? Make an explicit default (and configurable) shard uuid
and migrate to that?

-- 
Chris Dent                       Ù©â??̯â??Û¶           https://anticdent.org/
freenode: cdent                                         tw: @anticdent