On Fri, Nov 24, 2017 at 5:33 AM, Alexander Korotkov
<a.korotkov@postgrespro.ru> wrote:
> pg_prune_xid makes sense only for heap pages. Once we introduce special
> area for heap pages, we can move pg_prune_xid there and save some bytes in
> index pages. However, this is an optimization not directly related to
> 64-bit xids. Idea is that if we anyway change page format, why don't apply
> this optimization as well? But if we have any doubts in this, it can be
> removed with no problem.
My first reaction is that changing the page format seems like a
non-starter, because it would break pg_upgrade. If we get the heap
storage API working, then we could have a heap AM that works as it
does today and a newheap AM with such changes, but I have a bit of a
hard time imagining a patch that causes a hard compatibility break
ever being accepted.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
