On 29 Dec 2017, at 7:07pm, Ian Freeman <i...@ifreeman.net> wrote:
> Thanks, Simon. Indeed I did see that option. But I'm concerned about > maintaining integrity in the middle of an power-interrupted commit, This is not a problem for either WAL mode or the older journal modes. If you avoid these commands PRAGMA journal_mode = OFF PRAGMA journal_mode = MEMORY PRAGMA synchronous = OFF PRAGMA synchronous = NORMAL then SQLite will ensure that the database file always reflects your data as it was before the more recent COMMIT or after the most recent COMMIT. SQLite has a lot of code in to ensure the best handling in the case of power-loss. Each time a database file is reopened SQLite looks for tell-tales that it wasn’t properly closed, and uses a number of strategies to restore one of those two situations. This includes comparing the state of the database file with the states of the associated files (-wal, -shm, etc.). Because of this, do not delete/rename any of the associated files even when SQLite does not have them open. SQLite must be able to find these files /in the same folder as the database file/. If you ever back up one of those files, back them all up, including the database file, as a unit. They are useless without copies of all the other files as they were at the same time. Since the "synchronous" setting is default, the advice for installations where power-loss is not unexpected is to issue PRAGMA synchronous = EXTRA , to have the database in WAL mode if you want it (neither safer nor less safer with respect to power-loss), and leave everything else as it is. Simon. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
