Jeff Davis <pgsql@j-davis.com> writes:
> As I said elsewhere in the thread, I'm not planning to introduce any
> additional locking. There is already precedent in IndexOnlyNext.
Of course, that just begs the question of whether the code in
IndexOnlyNext is correct. And after looking at it, it seems pretty
broken, or at least the argument for its correctness is broken.
That comment seems to consider only the case where the target tuple has
just been inserted --- but what of the case where the target tuple is in
process of being deleted? The deleter will not make a new index entry
for that. Of course, there's a pretty long code path from marking a
tuple deleted to committing the deletion, and it seems safe to assume
that the deleter will hit a write barrier in that path. But I don't
believe the argument here that the reader must hit a read barrier in
between.
regards, tom lane