On Mon, May 3, 2021 at 9:45 AM Robert Haas <robertmh...@gmail.com> wrote: > But if you're saying those identifiers have to be fixed-width and 48 > (or even 64) bits, I disagree that we wish to have such a requirement > in perpetuity.
Once you require that TID-like identifiers must point to particular versions (as opposed to particular logical rows), you also virtually require that the identifiers must always be integer-like (though not necessarily block-based and not necessarily 6 bytes). You've practically ensured that clustered index tables (and indirect indexes) will never be possible by accepting this. Those designs are the only real reason to have truly variable-length TID-like identifiers IMV (as opposed to 2 or perhaps even 3 standard TID widths). You don't accept any of that, though. Fair enough. I predict that avoiding making a hard choice will make Jeff's work here a lot harder, though. -- Peter Geoghegan
