On 4 May 2015, at 4:09pm, Brandon <brandon at cogent3d.com> wrote: > We are using SQLite in an iOS app. We are not using the 'built-in' SQLite, we > are compiling from source. We have been battling an issue where the database > becomes 'malformed'. This occurs when iOS completely crashes (blue screen, > flickering, then restart). It's a pretty hard core crash. As a result - the > db often becomes malformed. My question is - is there anything I can do to > help prevent this? I have enabled 'WAL' mode. At this point, we are at a > loss. I am just not sure what our next step is.
You've hit a problem with iOS. iOS is a phone OS. It's not designed to crash, because the rules about phones say that they must always be available for calling the emergency number, so they mustn't crash. Given the no-crash rule for real-world performance and released Apps, it doesn't matter what happens if your App can crash the OS, because if it can crash the OS Apple will never approve it. So a phone OS often does things that computer OS would never do, like aggressive caching which doesn't bother to update main storage until the App backgrounds or quits. And this can lead to the type of corruption you're seeing. And since SQLite is doing everything it can to write to storage correctly, your fix cannot be done inside something SQLite is doing. So your 'treatment' for this problem is not to do with making SQLite more trustworthy. It's to figure out how you're crashing iOS and stop doing it. You're going to have to do that sooner or later anyway, because your App will never get through Apple's approval process for App distribution if it crashes iOS. If you think one of your SQLite calls is causing the crash we can help you. Do you have any idea what you're calling and under what circumstances it's happening ? If the thing crashing iOS is not to do with SQLite then you might be better off asking elsewhere. Simon.
