Doug McNaught <doug@mcnaught.org> writes:
> Short answer: MVCC tuple visibility status isn't (and can't be) stored
> in the index.
Well, in principle it *could* be, but there are strong arguments why it
shouldn't be: the costs of updating N index entries instead of just one
tuple entry, the potential reliability hit (what happens when the index
entries disagree with the master?), and the increase in index size
(adding an extra dozen bytes to an index entry is a very nontrivial
I/O hit).
I don't say we wouldn't ever do it, but it will take a lot more than
newbies opining that it might be a good idea to persuade us that it
is a good idea.
regards, tom lane