Re: Increasing IndexTupleData.t_info from uint16 to uint32

Montana Low <montana(at)postgresml(dot)org> writes:
> I've attached a patch that increases IndexTupleData.t_info from 16bits to
> 32bits allowing for significantly larger index tuple sizes.

I fear this idea is a non-starter because it'd break on-disk
compatibility. Certainly, if we were to try to pursue it, there'd
need to be an enormous amount of effort spent on dealing with existing
indexes and transition mechanisms. I don't think you've made the case
why that would be time well spent.

On a micro level, this makes sizeof(IndexTupleData) be not maxaligned,
which is likely to cause problems on alignment-picky hardware, or else
result in space wastage if we were careful to MAXALIGN() everywhere.
(Which we should have been, but I don't care to bet on it.) A lot of
people would be sad if their indexes got noticeably bigger when they
weren't getting anything out of that.

regards, tom lane