Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> That's definitely sucky, but in some ways it would be more complicated
> if they did, because I don't think all-visible on the master implies
> all-visible on the standby.
Ouch. That seems like it could shoot down all these proposals. There
definitely isn't any way to make VM crash-safe if there is no WAL-driven
mechanism for setting the bits.
I guess what we need is a way to delay the application of such a WAL
record on the slave until it's safe, which means the record also has to
carry some indication of the youngest XMIN on the page.
regards, tom lane