Re: [WIP] [B-Tree] Keep indexes sorted by heap physical location

On Mon, Nov 21, 2016 at 5:15 PM, Claudio Freire <klaussfreire(at)gmail(dot)com> wrote:
>> There are a couple
>> of tricky issues with that that you'd have to look out for, like
>> making sure that the high key continues to hold a real TID, which at a
>> glance looks like something that just happens already. I'm not sure
>> that we preserve the item pointer TID in all cases, since the current
>> assumption is that a high key's TID is just filler -- maybe we can
>> lose that at some point.
>
> I thought long about that, and inner pages don't need a real TID in
> their keys, as those keys only specify key space cutoff points and not
> real tids, and high tids in leaf pages are always real.

Not if there are duplicates in the inner pages. Then, you have to add
in the TID, and separate the key space, to guide insertions to the
right leaf page directly (particularly for non-HOT UPDATEs). That's
what I'm mostly interested in investigating, here.

--
Peter Geoghegan