On Mon, 2013-11-18 at 22:54 -0700, Keith Medcalf wrote:
> >Since I run all of these statements withing transactions (between
> >"BEGIN" statements and "COMMIT" / "ROLLBACK" statements"), my
> >expectation is that SQLITE_BUSY will only ever be returned for
> >the leading "BEGIN" statement.
>
> SQLITE_BUSY may be returned, for example, if the transaction is attempted to
> be upgraded from a read transaction into a write transaction, and an update
> lock cannot be obtained.
>
> "BEGIN" only begins a read transaction. "BEGIN IMMEDIATE" begins a
> transaction and obtains update locks immediately.
>
Thanks for the slightly more definitive answer than I could get on IRC.
It doesn't exactly answer my question though.
More precisely then, in the case that a read transaction is upgraded
to a write transaction, either by issuing an INSERT/DELETE command
or by issuing a nested BEGIN IMMEDIATE command, is it safe to retry
sqlite3_exec() until SQLITE_BUSY is not returned anymore ?
Or, must the entire transaction be retried from the beginning,
in the case that SQLITE_BUSY is returned at the point of this
upgrade from read to write transaction ?
> What the documentation is saying however is a word to the wise: Always check
> your return codes, and always deal with every situation that you can foresee.
> If a situation arises for which you are not prepared then die -- as
> expeditiously and as noisily as possible.
Yes, good general advice of course.
My particular interest here is to handle SQLITE_BUSY gracefully
so that callers of my library don't have to deal with it.
Similar to how one normally would check (errno == EINTR) in
a read()/write() loop and keep writing until finished, or until
an error from which one cannot recover, occurs (instead
of propagating the cumbersome error up the call chain).
You seem to suggest that I should fail loudly in the case
of SQLITE_BUSY, this is exactly what I want to avoid.
Cheers,
-Tristan
>
>
>
> _______________________________________________
> 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
