On Tue, Sep 13, 2011 at 19:34, Robert Klemme <shortcutter@googlemail.com> wrote:
> I don't think so. You only need to catch the error (see attachment).
> Or does this create a sub transaction?
Yes, every BEGIN/EXCEPTION block creates a subtransaction -- like a
SAVEPOINT it can roll back to in case of an error.
> Yes, I mentioned the speed issue. But regardless of the solution for
> MySQL's "INSERT..ON DUPLICATE KEY UPDATE" which Igor mentioned you
> will have the locking problem anyhow if you plan to insert
> concurrently into the same table and be robust.
In a mass-loading application you can often divide the work between
threads in a manner that doesn't cause conflicts.
For example, if the unique key is foobar_id and you have 4 threads,
thread 0 will handle rows where (foobar_id%4)=0, thread 1 takes
(foobar_id%4)=1 etc. Or potentially hash foobar_id before dividing the
work.
I already suggested this in my original post.
Regards,
Marti
