Re: crash-safe visibility map, take three

Robert Haas <robertmhaas@gmail.com> writes:
>  If we switched from per-tuple MVCC based on XIDs to per-page MVCC
> based on LSNs and a rollback segment, all of this stuff would go out
> the window.  Hint bits, gone.  Anti-wraparound VACUUM, gone.  CRCs,
> feasible.  Visibility map... we might still need that, but the
> page-level bits go away.

> Of course, it would also create new problems.

Yup, we've seen that proposal before.  It's called Oracle.  There's
no good reason to believe that we'd have a net win after we were done
switching over ... not to mention the likelihood that they hold a ton
of patents about particular aspects of doing things that way.
        regards, tom lane