Re: [CORE] FOR SHARE vs FOR UPDATE locks

Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Josh Berkus wrote:
>> So, I think it needs to go on the list for 8.2.1 or 8.3 (depending on what
>> changes the fix requires) but I don't think we should hold up the release.

> We cannot add something this major in a minor release --- it would have
> to be 8.3.

If someone thinks of a brilliant solution that doesn't change on-disk
layout, maybe we could implement it in 8.2.x, but right now I'm not
feeling hopeful about that.

The best idea I have at the moment is that we might be able to do
something as part of the proposed plan to fold cmin/cmax into a single
field. The thought there was that there could be some in-memory state
for tuples that had been modified multiple times by a single xact ---
perhaps that could be extended to cover this problem. This is just
handwaving at the moment though. In particular, is-the-tuple-locked-or-not
seems like it has to be externally visible state, so maybe it can't work.

regards, tom lane