I can see the .wal and .shm files getting created and don't see a reason why SQLite would suddenly have issues accessing those files.
The error does not come up immediately, creating tables works fine, making inserts works fine, it's only when I start making updates (from multiple threads) where this error starts showing up. // Sascha On Fri, Oct 4, 2013 at 12:53 PM, Dan Kennedy <[email protected]> wrote: > On 10/05/2013 01:55 AM, Sascha Sertel wrote: > >> Hello everybody, >> >> I'm hoping someone might have some insights on a particular issue I've >> been >> running into. Here some details: >> >> I'm working on a multi-platform app that uses a cross-platform library >> with >> SQLite 3.7.16.1 built into it (i.e. not using the built-in SQLite version >> in Android or other platforms). We make (re)use of prepared statements for >> INSERT and UPDATE on the database, and we use FULLMUTEX serialized >> threading mode. We use explicit transactions for some bulk INSERT >> operations, but most other calls use implicit transactions. >> >> Everything worked fine until I switched journal_mode from MEMORY to WAL. >> Now when I run the app I started seeing SQLite errors pop up, the first >> error is >> >> >> sqlite3_step failed: unable to open database file (error code: 14) >> > > That error usually indicates that SQLite failed to open > or create some require file. Is there some reason the app > might fail to open or create a *-wal or *-shm file in the > same directory as the database file? > > Dan. > > > > > >> >> and after that I get a lot of follow-up errors from my prepared statements >> such as >> >> >> sqlite3_bind_text failed: library routine called out of sequence >> (error code: 21) >> >> >> This does not happen on iOS or other platforms using the same >> cross-platform library, leading me to believe this might be an Android >> specific issue, maybe due to VFS differences or something like that. >> >> There are multiple threads in the same process accessing the database, all >> using the same shared connection. My understanding is that due to the >> FULLMUTEX mode SQLite is serializing all these calls. Now WAL basically >> reenables concurrent reads and writes, my suspicion is that the error is >> caused by trying to do concurrent writes even though it shouldn't. >> However, >> in that case I would expect to see a database locked error instead of this >> weird unable to open database file issue. >> >> Does any of this sound familiar to anyone? I wasn't able to fix it by any >> means other than setting journal_mode back, actually all other journaling >> modes work fine except WAL. I looked around and couldn't really find much >> on people having issues with WAL on Android, so it might be something >> about >> the combination of WAL with prepared statements and FULLMUTEX? >> >> Any help is appreciated! >> >> // Sascha >> ______________________________**_________________ >> sqlite-users mailing list >> [email protected] >> http://sqlite.org:8080/cgi-**bin/mailman/listinfo/sqlite-**users<http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users> >> > > ______________________________**_________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-**bin/mailman/listinfo/sqlite-**users<http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users> > _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
