Re: Core Data versioning woes
Re: Core Data versioning woes
- Subject: Re: Core Data versioning woes
- From: Steve Steinitz <email@hidden>
- Date: Mon, 11 Aug 2008 12:32:07 +1000
Hello Mr Crawford,
Oops, didn't want to hijack Graham's nice clean thread. However...
On 10/8/08, mmalc crawford wrote:
ps. one special problem I have is that I don't want the migration to
happen automatically because four users share the same database.
<http://developer.apple.com/documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/vmInitiating
.html#//apple_ref/doc/uid/TP40005509-SW2>
"If your application does support versioning and you choose to use
custom version skew detection and migration bootstrapping, before
opening a store you should check (using
isConfiguration:compatibleWithStoreMetadata:) whether its schema is
compatible with the coordinator’s model: if it is, you can use
addPersistentStoreWithType:configuration:URL:options:error: to open
the store directly; if it is not, you must migrate the store first
then open it (again
usingaddPersistentStoreWithType:configuration:URL:options:error:)."
Thanks for looking up that reference. I saw it when I printed
out and
carefully read the versioning document, text marker in hand. I confess,
I only understood about 25% of it, felt it lacking and
discovered that
the process, as described, didn't work -- at least in my
non-document-based app, as described in another thread.
With the delicate state of the built-in versioning/migration
code, i.e.
treacherous to get it working at all, 'version skew detection' and
'migration bootstrapping' sound scary :) and lack definitions,
let alone
explanations & sample code, in the documentation.
Moreover, I don't see how the referenced doc snippet relates to my
multi-user scenario -- I really wish I did. Regardless of
whatever it
is trying to say, I would be nervous migrating automatically with
multiple users. Do you disagree? Having everyone quit the app
while I
do the migration makes me more comfortable. Then, they can Sparkle
(update) their app to the latest version and access the newly-migrated
database.
Thanks again,
Steve
ps. Sorry, Graham, for the brief hijack
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