On 2018/05/08 11:32 AM, Rowan Worth wrote:
On 8 May 2018 at 17:22, R Smith <ryansmit...@gmail.com> wrote:
On 2018/05/08 9:37 AM, Donald Shepherd wrote:
It would actually be real nice if the backup API had a parameter or flag
like "sqlite3_lockduringbackup".
Not quite right. sqlite3_backup_step accepts a number of pages to be copied
by the current invocation. If you specify a negative number of pages,
sqlite3_backup_step will obtain a read lock and copy the entire database
before returning. So the "lock during backup" mode already exists - the
only way you get the backup restarting behaviour is if you ask
sqlite3_backup_step to copy a subset of the database.
Thank you for clarifying - but it is still my understanding that the DB
is not locked (if only in WAL mode), so the backup API, even with -1,
either must ignore changes, or restart. My proposed flag is to lock
rather than restart or ignore.
That said, it's hardly important - can be accomplished in controlling
software and only serves a small number of use cases - but the API is
best placed to effect the request. Perhaps place it on the
"nice-to-have-someday" TO-DO list.
Cheers,
Ryan
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