On 2011-04-13, at 15:53, Richard Hipp wrote: > On Wed, Apr 13, 2011 at 10:33 AM, Simon Slavin > <slav...@bigfraud.org> wrote: > >> >> On 13 Apr 2011, at 12:14pm, James Green wrote: >> >>> sync=full does not work well for our app (no transactions). Far >>> too slow. >> >> If you're not syncing, then section 3.2 of the page Richard probably >> indicates what's causing your corruption. >> > > We have assumed that disabling synchronous requires a power failure > or hard > reset in order to cause corruption. But that is based on the > premise that > operating system disk case is coherent. In other words, if two > processes > running on the same machine have the same disk file open, and if > process A > writes pages 1 and 2, in that order, and process B reads pages 1 and > 2 at > the same time, then process B will either see none of A's change, or > B will > see the changes to page 1 and not page 2, or B will see both > change. It > will never be the case that B will see the changes to page 2 but not > the > changes to page 1. > > Can somebody please confirm for me that windows works this way? > > If it turns out that I'm wrong and the windows disk cache is not > coherent, > then you will indeed need to set synchronous=FULL on windows in > order to > prevent corruption. Or, perhaps we can find some magic I/O barrier > system > call for windows that we can insert in place of the > FlushFileBuffers() when > synchronous is OFF. But for now, until I get better information, > I'm going > to assume that he windows disk cache is indeed coherent and that > none of > this is necessary. > [...]
Sorry to chip in again, Richard, but would you kindly send me a personal email on these issues. I know a thing or two about the intricacies of operating systems and have extensive experience of using SQLite (and many other databases) in non-robust environments. I would like to offer suggestions to help the original poster to solve the problem, but my lack of diction makes me unable to word my questions and suggestions in the right manner for this forum. Kindest regards to you all, Pete _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
