Re: Stability of auto IDs

Hallöchen!

Steve Holden writes:

> On 7/27/2010 12:38 PM, Torsten Bronger wrote:
>> Hallöchen!
>>
>> bruno desthuilliers writes:
>>
>>> On 27 juil, 07:19, Torsten Bronger <bron...@physik.rwth-aachen.de>
>>> wrote:
>>>
>>>> Currently, our Django app relies on the stability of various auto
>>>> ID fields which are implicitly generated by Django/database
>>>> backend.
>>>
>>> [...] From a practical POV, starting from a mint empty DB and
>>> inserting records in the same order without any other client app
>>> accessing to the DB, you should probably get the same IDs, but
>>> there's absolutely no garantee.
>>
>> At least, they are explicitly mentioned in a "manage.py dumpdata"
>> fixture, and probably in a SQL dump, too. But the DB may ignore
>> autofields when loading that data, right?
>
> It couldn't do that without ruining the relationships, could it? A
> dump includes the numerical values for the foreign keys, so the
> related primary keys have to stay the same to maintain relational
> integrity.

Well, it could map them possibly ... granted that there would be no
reason for it. Okay, then I must be more precise:

If I have a model with an implicit primary key, and values of this
key are used to identify associated files on disk, is this safe?
Safe as far as restoring SQL backups, re-loading fixtures, and south
migrations are concerned?

Tschö,
Torsten.

--
Torsten Bronger, aquisgrana, europa vetus
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