Open Stack

On Mon, Mar 10, 2014 at 7:11 AM, Matt Riedemann
<mriedem at linux.vnet.ibm.com> wrote:
>
>
> On 3/9/2014 9:18 PM, Jay Pipes wrote:
>>
>> On Mon, 2014-03-10 at 10:05 +0800, ChangBo Guo wrote:
>>>
>>>
>>>
>>>
>>> 2014-03-10 4:47 GMT+08:00 Jay Pipes <jaypipes at gmail.com>:
>>>
>>>
>>>          > 3. This would make the instances and shadow_instances tables
>>>          have
>>>          > different schemas, i.e. instances.uuid would be
>>>          nullable=False in
>>>          > instances but nullable=True in shadow_instances.  Maybe this
>>>          doesn't matter.
>>>
>>>
>>>          No, I don't think this matters much, to be honest. I'm not
>>>          entirely sure
>>>          what the long-term purpose of the shadow tables are in Nova --
>>>          perhaps
>>>          someone could clue me in to whether the plan is to keep them
>>>          around?
>>>
>>>
>>> As I know the tables shadow_*  are used  by command ' nova-manage db
>>> archive_deleted_rows' , which moves  records with "deleted=True" to
>>> table shadow_* . That means these tables are used by other  process,
>>> So, I think we need other tables to store the old records in your
>>> migration.
>>
>>
>> Yeah, that's what I understood the shadow tables were used for, I just
>> didn't know what the long-term future of these tables was... curious if
>> there's been any discussion about that.
>>
>> Best,
>> -jay
>>
>>
>>
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>>
>
> I think Joe Gordon was working on something in the hopes of eventually
> killing the shadow tables but I can't remember exactly what that was now.

I haven't been working on this but I do have a plan.

Originally we couldn't hard delete anything in nova DB, because people
wanted to keep the records around for well record keeping. The long
term solution is make nova support (although not default to) hard
delete. This means we need another place to store these records
(ceilometer). Until then, we have shadow tables as a short term
solution. If you want to keep records around but don't want them in
your main nova DB.

On a related note, nothing in nova should actually be using soft
deleted data or shadow tables, any cases should be treated as bugs.



>
> --
>
> Thanks,
>
> Matt Riedemann
>
>
>
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