> Pavel, please tell me you are wrong. Surely windows maintains disk cache > coherency even in the absence of explicit FlushFileBuffers() calls?
I'm sorry, I've got this idea from some post on this list. And only after I wrote the email I've realized how scary it could be if it worked this way. Pavel On Wed, Apr 13, 2011 at 10:25 AM, Richard Hipp <d...@sqlite.org> wrote: > On Wed, Apr 13, 2011 at 9:53 AM, Pavel Ivanov <paiva...@gmail.com> wrote: > >> > The fact that one engineer installed a site, began operating the app, >> > then saw it become corrupt minutes later rules out power loss or hard >> > resets in at least that case. An operating system level problem should >> > have been noticed by now given it's Windows XP... And the file is >> > locally held too. >> >> I don't know how Windows's disk cache works but theoretically when you >> set synchronous to OFF (0) OS can write database pages to disk in any >> order it likes, disregarding the order SQLite requires. So while one >> process writes those pages, another process can read those pages and >> because of random writing order second process can read inconsistent >> data, meaning it sees corrupted database. >> > > Pavel, please tell me you are wrong. Surely windows maintains disk cache > coherency even in the absence of explicit FlushFileBuffers() calls? > > Can any windows experts comment on this? > > > >> >> >> Pavel >> >> >> On Wed, Apr 13, 2011 at 7:14 AM, James Green <james.mk.gr...@gmail.com> >> wrote: >> > Yep we've read through that. >> > >> > Several of the possibilities are difficult to rule out of course. They >> > just seem highly unlikely (!) given the rate of corruption across our >> > sites. >> > >> > The fact that one engineer installed a site, began operating the app, >> > then saw it become corrupt minutes later rules out power loss or hard >> > resets in at least that case. An operating system level problem should >> > have been noticed by now given it's Windows XP... And the file is >> > locally held too. >> > >> > Is it possible that we're seeing something nasty occurring as a result >> > of anti-virus software perhaps? I might expect a higher rate of >> > corruption if so. >> > >> > The only avenue apparently open to us is to use WAL mode. Would WAL + >> > sync=normal provide a much better resistance to corruption? We >> > (probably) don't care about losing the last set of SQL statements. >> > >> > sync=full does not work well for our app (no transactions). Far too slow. >> > >> > James >> > >> > On 13 April 2011 11:47, Richard Hipp <d...@sqlite.org> wrote: >> >> On Tue, Apr 12, 2011 at 5:15 AM, James Green <james.mk.gr...@gmail.com >> >wrote: >> >> >> >>> My question is does anyone have pointers >> >>> to help us isolate the problems we are seeing. >> >>> >> >> >> >> http://www.sqlite.org/howtocorrupt.html >> >> >> >> -- >> >> D. Richard Hipp >> >> d...@sqlite.org >> >> _______________________________________________ >> >> 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 >> > >> _______________________________________________ >> sqlite-users mailing list >> sqlite-users@sqlite.org >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >> > > > > -- > D. Richard Hipp > d...@sqlite.org > _______________________________________________ > 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
