On Wed, Jun 25, 2014 at 2:19 PM, Igor Tandetnik <i...@tandetnik.org> wrote:
> On 6/25/2014 5:19 AM, João Ramos wrote: > >> And I understand the limitations a shared-cache mode may have, but if this >> is to be the case, it should be documented. I can be wrong, but I didn't >> find anywhere in the docs where this scenario is presented (or has some >> sort of warning). >> > > Well, one can't document every possible scenario, every possible > interaction of various features. There's a documentation on shared cache, > complete with a nice picture explaining how all connections to the cache > share a single connection to the underlying database file: > > http://sqlite.org/sharedcache.html > "Externally, from the point of view of another process or thread, two or > more database connections using a shared-cache appear as a single > connection. The locking protocol used to arbitrate between multiple > shared-caches or regular database users is described elsewhere." > Of course and I understand what your saying, and I'm not asking to document every single feature interaction. However, the documentation never mentions the possibility of data visibility changes caused by the shared-cache mode and, in my opinion, it's a big enough issue that should merit being referenced in the documentation. > > Then there's documentation on WAL mode, explaining how it is possible for > a writer to co-exist with readers, via page versioning. > > http://www.sqlite.org/wal.html Now that you mentioned the WAL, shouldn't this actually help prevent this scenario? I've never looked at SQLite implementation, but if a transaction starts after a successful commit (T1), the new data it tries to access shouldn't be cached because it was just now written to the WAL, correct? > > > If you use both features, you kind of have to put two and two together to > see how they would interact. Well, the way I see it, it's more like a 10 variable equation: not that obvious. But that could be just me. > > -- > Igor Tandetnik > > _______________________________________________ > 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
