Re: Core Data and Document Packages
Re: Core Data and Document Packages
- Subject: Re: Core Data and Document Packages
- From: "Timothy J. Wood" <email@hidden>
- Date: Tue, 3 Jul 2007 18:55:10 -0700
On Jul 3, 2007, at 1:38 AM, Seth Willits wrote:
My document-based app has a document type which uses a package
instead of just a single file to store data in, because there is a
need to store related files inside the package as well. Currently
I'm doing some relatively simple overloading of standard NSDocument
methods to open and save the database by using a path based off of
the -fileName.
One major problem with using file wrappers is ensuring atomic
saves. If one of your save operations needs to update SQLite and add/
remove/update other files in the file wrapper, the only real option
would be to make a copy of the entire wrapper, apply the changes
(including the SQLite transaction) to the copy and then atomic swap
the two wrapper directories using FSExchangeObjects or the like. At
this point, you've lost most of the benefit of putting it in a SQLite
database (at least in terms of save speed; there are obviously other
benefits).
What I wouldn't give for a transactional filesystem with copy-on-
write...
-tim
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