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: "Gustavo Vera" <email@hidden>
- Date: Thu, 14 Aug 2008 01:33:25 -0300
Well, I´m aware that problems in the future are a possibility with the
approach I choose to take. That´s the reason why I´m trying to take all the
cares I can to avoid those future problems as much as I can. In the mean
time, I´m winning a lot of time by avoiding using or implementing the
"possible but tedious" (I´m citing Jim Correia here) migration
functionalities using the Core Data API directly. I know the advantages and
disadvantages, and I´m ready to "pay the price" when that moment arives. I´m
aware that I don´t have a full understand of the underlying sqlite
structure, but I know (and learned) enough to keep using my approach. I´m
just trying to increase my knowledge to extend in time my capacity of using
the current approach.
Does anybody know if the original designers of the underlying sqlite
structure are available to clarify some details about it? Just in case?
By the way, thanks for the Leopard Core Data migrator info, I´m gonna check
that when the moment of porting to Leopard arrives (for the moment, we are
developing this app on and for Tiger only).
Thanks to everybody for your suggestions!
On Wed, Aug 13, 2008 at 6:49 PM, Louis Gerbarg <email@hidden> wrote:
> 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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