On Thu, Dec 28, 2017 at 3:59 PM, Simon Slavin <slav...@bigfraud.org> wrote: > On 28 Dec 2017, at 8:10pm, Chris Brody <chris.br...@gmail.com> wrote: > >> [...] >> But I wondered if WAL may be more robust against possible sqlite >> corruption, in theory or in practice.
After sending I found a couple threads that *seem* to confirm that WAL mode may be more reliable against possible corruption: * http://sqlite.1065341.n5.nabble.com/WAL-mode-is-reliable-td41264.html * https://marc.info/?l=sqlite-users&m=132052237302135&w=2 >> Any comments? > > WAL mode makes SQLite neither more nor less liable to corruption. You should > not be seeing corruption in SQLite no matter what mode it’s in. Thanks Simon for the response. I just found it today, unfortunately directed to my spam folder. Makes sense, assuming there is nothing wrong according to the "how to corrupt" checklist. > If you want a PRAGMA to strengthen against corruption, try "PRAGMA > synchronous = FULL": > > <https://www.sqlite.org/pragma.html#pragma_synchronous> I will guess you meant to try "PRAGMA synchronous = EXTRA" (seems to be FULL by default). Maybe a good idea in a hybrid mobile application environment. > If you are seeing corruption, you might want to see this checklist. > > <https://www.sqlite.org/howtocorrupt.html> Right. The challenge for me is that my users are JavaScript developers, often with very limited native platform experience. > Given that you’re running on a phone/tablet, emphasis is on handling > suspension (backgrounding) and termination of the app properly. There are > people here experienced with using SQLite on iPhone and Android who can > criticise your approach. > > If nothing obvious occurs to you, please post some details: which platform, > which circumstances, are you doing multi-thread or multi-process, do you > check result codes for your API calls, are you getting error results ? > > Simon. In general I would expect that the app may be suspended or terminated with no advance notice due to the hybrid environment they run in. I think the Cordova/PhoneGap framework should give some form of notification but I would not trust this mechanism to be 100% reliable. I also want the apps to be robust against possible crashes, memory issues for example. Right now I am thinking it would be safest to use "PRAGMA synchronous = EXTRA" at the beginning, feedback would be highly appreciated. The hybrid JavaScript/native SQLite API component I maintain is available in the following location: https://github.com/litehelpers/Cordova-sqlite-storage This component acts as a bridge between JavaScript and native code on Android, iOS, and Windows. I am in the middle of some updates and the documentation really needs cleanup at this point. Right now it is using one background thread per database on Android, dynamic background threads on iOS, no form of background threading on Windows. I already fixed a couple possible causes of corruption on iOS as discussed in: - https://github.com/litehelpers/Cordova-sqlite-storage/issues/703 - https://github.com/litehelpers/Cordova-sqlite-storage/issues/716 Reports of database corruption have been extremely rare in this project but I just wanted to check how to make it as safe as possible. Chris _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
