On Tue, Apr 3, 2018 at 7:02 AM, Peter Geoghegan <pg@bowt.ie> wrote:
On Mon, Apr 2, 2018 at 4:27 PM, Alexander Korotkov <a.korotkov@postgrespro.ru> wrote: > I thought abut that another time and I decided that it would be safer > to use 13th bit in index tuple flags. There are already attempt to > use whole 6 bytes of tid for not heap pointer information [1]. Thus, it > would be safe to use 13th bit for indicating alternative offset meaning > in pivot tuples, because it wouldn't block further work. Revised patchset > in the attachment implements it.
This is definitely not the only time someone has talked about this 13th bit -- it's quite coveted. It also came up with UPSERT, and with WARM. That's just the cases that I can personally remember.
I'm glad that you found a way to make this work, that will keep things flexible for future patches, and make testing easier. I think that we can find a flexible representation that makes almost everyone happy.
OK, good.
I didn't have time to look at this properly today, but I will try to do so tomorrow.