Re: What's the use of the Z_UUID in the Z_METADATA table?
Re: What's the use of the Z_UUID in the Z_METADATA table?
- Subject: Re: What's the use of the Z_UUID in the Z_METADATA table?
- From: "Louis Gerbarg" <email@hidden>
- Date: Wed, 13 Aug 2008 17:49:07 -0400
Performing migrations by altering the underlying structure of files you do
not understand will most likely result in data corruption. Even if the file
appears to work correctly now, that does not mean it is correct, and it does
not mean that it will continue to work in the future, especially if you have
violated any assumption that future schema migrators make about the DB file.
Louis
On Wed, Aug 13, 2008 at 9:56 AM, Gustavo Vera <email@hidden> wrote:
> Maybe I should not, but I'm doing it anyway :D
> I'm looking inside and also I'm manipulating the structure and data of the
> sqlite file since about 200 revisions in my project. I'm doing this to
> provide newer versions of the app that has the possibility of performing
> database migrations / upgrades from older versions of the app if available.
> With the new functionalities, occasionally a change in the database
> structure results necessary, and when the change is simple (for example,
> just adding a new attribute to an entity) altering the data model and the
> data structures in an old sqlite is far easier and faster than implementing
> the migration functionality suggested in the documentation. In fact, I
> think
> this is faster and easier even when more complex changes are necessary.
> Anyway... I was wondering if I should take care of the Z_UUID during the
> perform of this upgrades, or if I can just ignore it. I'm currently
> ignoring
> it... can this become a problem in the future?
>
>
> On Tue, 12 Aug 2008 17:28:39 -0300, Marcelo Alves
> <email@hidden> wrote:
>
> >
> > It is a implementation detail. You should not look inside the sqlite
> file.
> >
> > 2008/8/12 Gustavo Vera <email@hidden>:
> > > What's the use of the Z_UUID in the Z_METADATA table?
> > > Is some kind of check sum or something like that?
> > > CoreData uses this value for something?
> > > Why is this value different every time the DB is regenerated?
> > > Is the generation of it a random-based one? Or is it based on
> > > random+"another thing"?
> > >
> > > Please don't answer my question with another question!!! At least not
> at
> > > first instance! :D
> > >
> > > Thanks in advance!
> >
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