[openstack-dev] [Nova] sqlalchemy-migrate vs alembic for new database

Sylvain Bauza sbauza at redhat.com
Fri Dec 5 20:52:23 UTC 2014


Le 05/12/2014 21:14, Matt Riedemann a écrit :
>
>
> On 12/5/2014 1:45 PM, Andrew Laski wrote:
>> The cells v2 effort is going to be introducing a new database into
>> Nova.  This has been an opportunity to rethink and approach a few things
>> differently, including how we should handle migrations. There have been
>> discussions for a long time now about switching over to alembic for
>> migrations so I want to ask, should we start using alembic from the
>> start for this new database?
>>
>> The question was first raised by Dan Smith on
>> https://review.openstack.org/#/c/135424/
>>
>> I do have some concern about having two databases managed in two
>> different ways, but if the details are well hidden behind a nova-manage
>> command I'm not sure it will actually matter in practice.
>>
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>>
>
> I don't have experience with Alembic but I'd think we should use 
> Alembic for the new database unless there is a compelling reason not 
> to. Maybe we need Mike Bayer (or other oslo.db people) to give us an 
> idea of what kinds of problems we might have with managing two 
> databases with two different migration schemes.
>
> But the last part you said is key for me, if we can abstract it well 
> then hopefully it's not very painful.
>


I had some experience with Alembic in a previous Stackforge project and 
I'm definitely +1 on using it for the Cells V2 database.

We can just provide a nova-manage cell-db service that would facade the 
migration backend, whatever it is.





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