Simon Riggs wrote:
> Rather than signalling, we could use a hasconflict boolean for each proc
> in a shared data structure. It can be read without spinlock, but should
> only be written while holding spinlock.
>
> Each time we read a block we check if hasconflict is set. If it is, we
> grab spinlock, recheck if it is set, if so read the conflict details,
> clear the flag and drop the spinlock.
Yeah, that seems workable.
> The aim of this type of conflict resolution was to reduce the footprint
> of users that would be effected and defer it as much as possible. We've
> spent time getting the latestCompletedXid, but we know deriving that
> value is very difficult in the btree case at least. So what I would like
> to do is pass the relid of a conflict across as well and use that to
> reduce the footprint, now that we are performing the test inside the
> buffer manager.
I agree that would be useful, but I'd prefer to keep it simple for now...
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
