On Thu, Jun 5, 2014 at 7:21 AM, Lasse Jansen <la...@lasselog.com> wrote:
> Hi, > > we have a Mac app that uses CoreData which internally uses SQLite. Some of > the queries are not expressible within CoreData, so we send them manually > using the sqlite library that comes with Mac OS X. Now some of our users > have reported that their database file got corrupted and after some > researching I think it's because of multiple copies of SQLite being linked > into the same application as described here: > > http://www.sqlite.org/howtocorrupt.html > > Even though we link CoreData to our application and CoreData uses sqlite > internally we still have to explicitly link libsqlite as the CoreData > version of sqlite is inaccessible due to the usage of > two-level-namespacing. > > So I have two questions: > 1. Can this be solved without dropping CoreData? > 2. If not, is there a workaround that we could use until we replaced > CoreData with something of our own? > > I'm thinking of this: > As the problem seems to occur due to calling close() and we only use > libsqlite for read-only access, would just not closing the read-only > database connection prevent the corruption? > The problem is more than just close(), unfortunately. Certainly the fact that close(open(zFilename)) deletes all locks on any file descriptor for the same file is a big problem. But it is not the only problem. fcntl(F_SETLK) has its own set of similar problems. Now if you did this: (1) Open the read-only connection using the brand-new "nolock" option available in 3.8.5 (to disable the use of fcntl(F_SETLK). (2) Keep the read-only connection open forever, or at least until after all coredata connections are open. Then it might work. However, with locking disabled, your read-only connection might try to read the database file simultaneously with other process writing it, which would make the read-only connection think that the database is corrupt. This would be a difficult thing to clear without closing and reopening the database connection, unfortunately. -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
