Apple uses Sqlite in a number of applications, including Apple Mail, so they have to have some kind of accommodation for saving sqlite databases.
The Time Machine patent does not describe using file system snapshots: *"An algorithm or other monitoring can be used to detect changes that occur during the backup operation in order to maintain consistency between related data in the backup. The back up can be performed again for related data that was modified during prior backup operation. * *"In general, in one aspect, a method is provided. A backup operation of data including a plurality of related items is initiated. Modifications to one or more items of the plurality of related items are monitored for during the backup operation. The backup operation is completed. If a modification occurred to one or more items, a second backup operation is performed for the modified items."* This does not seem to authoritatively state that multiple files will be backed up consistently. On Wed, Dec 12, 2018 at 9:06 AM Keith Medcalf <kmedc...@dessus.com> wrote: > > I know nothing about "Time Machine", but does it copy the entire > filesystem in (at least) "crash consistent" state? > > --- > The fact that there's a Highway to Hell but only a Stairway to Heaven says > a lot about anticipated traffic volume. > > > >-----Original Message----- > >From: sqlite-users [mailto:sqlite-users- > >boun...@mailinglists.sqlite.org] On Behalf Of Daniel Alm > >Sent: Tuesday, 11 December, 2018 05:02 > >To: sqlite-users@mailinglists.sqlite.org > >Subject: [sqlite] Mac: Users receive "database disk image is > >malformed" errors after restoring database from Time Machine backup > > > >Hi, > > > >For the past half year we’ve been receiving reports from users who > >had restored their SQLite-based databases from a Time Machine backup. > >Afterwards, they would receive "database disk image is malformed” > >errors. The app also backs up the user’s data “manually” to a ZIP > >file every week; those backups seem to be working fine. We also > >haven’t received reports from other backup tools causing issues. I > >have also suspected a bug in Time Machine, but it is striking that > >the issues did seem to start occurring after an update to the app > >(luckily, in fact, with the same update that also introduced the > >“manual” backups). > > > >Changes that we made to our setup in the update that coincided with > >the errors occurring: > >- Upgraded SQLite from 3.21 to 3.24 (we have since reverted to 3.23.1 > >in another update; no improvement). > >- Used memory mapping for read accesses via “PRAGMA mmap_size = > >1073741824;” (we have since reverted to “PRAGMA mmap_size = 0;” after > >reading http://sqlite.1065341.n5.nabble.com/Re-Database-corruption- > >and-PRAGMA-fullfsync-on-macOS-td95366.html > ><http://sqlite.1065341.n5.nabble.com/Re-Database-corruption-and- > >PRAGMA-fullfsync-on-macOS-td95366.html>; no improvement). > >- Using a secondary database via [ATTACH > >DATABASE](https://www.sqlite.org/lang_attach.html > ><https://www.sqlite.org/lang_attach.html>) (although this also seems > >to occur for users without such a database). > > > >At this point, I am at a loss, especially given that SQLite should be > >fairly robust against database corruption. While our app is running > >in the background all the time, it is not very write-heavy (~ one > >transaction per minute taking just a few milliseconds). Also, the app > >had been running fine before the update for a long time without any > >reports of this issue. I might be doing something wrong or have > >changed anything else, but I don’t know what; if you have any ideas, > >let me know. > > > >Any suggestions on what could be the culprit or what else I could try > >besides downgrading all the way to SQLite 3.21 would be appreciated. > > > >Thanks, > >Daniel Alm > > > >P.S.: Our database currently uses the following PRAGMAs: > > > >PRAGMA mmap_size = 0; > >PRAGMA page_size = 4096; > >PRAGMA cache_size = -10240; > >PRAGMA foreign_keys = ON; > >PRAGMA journal_size_limit = 8388608; > >PRAGMA checkpoint_fullfsync = 1; > >PRAGMA wal_autocheckpoint = 2048; > >PRAGMA journal_mode = WAL; > > > >Happy to provide any more details as needed. > >_______________________________________________ > >sqlite-users mailing list > >sqlite-users@mailinglists.sqlite.org > >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
