Re: Remove xmin and cmin from frozen tuples

Tom Lane <tgl@sss.pgh.pa.us> wrote:

> I think this is incredibly ugly :-(.

Yes, I think so, too :-(    My patch is product of the thought that
I don't want to modify codes widely. So if we want to do it more cool way,
lots of changes are needed as you said.


> I'm also less than enthused about using up our last infomask bit for
> a relatively unimportant purpose.  We might need that for something
> bigger someday... though I can't presently guess what.

I think it is not a problem, because the header still has rooms for several
bits. I assume that the combination of HEAP_XMIN_COMMITTED + HEAP_XMIN_INVALID
has currently no meaning, right? If so, HEAP_FROZEN can be assigned here.
Also, t_natts is currently 16-bits, but it can be cut to 11-bits
because MaxTupleAttributeNumber is 1664 < 2^11.

---
ITAGAKI Takahiro
NTT Cyber Space Laboratories