This makes sense now, thanks. D. Richard Hipp, are there any plans to make this more robust in the future, so reading/writing a corrupt database (with no -journal file available) will return an *error* instead of causing further damage?
One idea: A "flag" could be added to the main database file to indicate that it has a corresponding -journal file. If it has the flag but no -journal file exists, that would be an error. To add the flag, Mac OS X has extended attributes. Not necessarily available on all filesystems, but a nice protection against corruption where available. What do you think? Possible? Impossible? ---------------------------------------- > From: d...@sqlite.org > Date: Sat, 30 Nov 2013 17:30:01 -0500 > To: sqlite-users@sqlite.org > Subject: Re: [sqlite] Concrete example of corruption > > On Sat, Nov 30, 2013 at 5:15 PM, L. Wood <lwoo...@live.com> wrote: > >> Thanks, that makes sense. >> >> But I can pretty much rule this case out. In my case, it's highly unlikely >> that the folder would be moved during the brief instant between _open() and >> the actual opening of the "-journal" file. >> >> Are there other possible cases of corruption? >> > > > > (1) Process A opens database at /first/path/to/database.db > (2) The directory is renamed to /second/path/to/database.db > (3) Process B begins writing to the database, creating a rollback journal > at /second/path/to/database.db-journal > (4) Process B crashes without committing or rolling back. > (5) Process A tries to read the database. It checks for a hot journal > file at /first/path/to/database.db-journal, finds none (since the hot > journal is now in a different place) and therefore does not know that it > needs to recover the database file. It sees the database as being corrupt. > Or if A tries to write to the database, it makes the corruption worse, such > that even a third process that does see the hot journal is no longer able > to recover. > > > -- > D. Richard Hipp > d...@sqlite.org > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
