"Mikheev, Vadim" <vmikheev@SECTORBASE.COM> writes:
> We could add transaction data to index tuples but this would increase
> their size by ~ 16bytes.
The increased space is the least of the drawbacks. Consider also the
time needed to maintain N copies of a tuple's commit status instead of
one. Even finding the N copies would cost a lot more than the single
disk transfer involved now ...
regards, tom lane