On Tue, Nov 30, 2010 at 11:59 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Tue, Nov 30, 2010 at 11:40 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> 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.
>> Heikki's intent method works fine, because the WAL record only clears
>> the visibility map bits on redo; it never sets them.
> Uh, no, because he also had that final WAL record that would set the
Well, as already discussed upthread, that WAL record causes some other
problems, so make it Heikki's intent method, without the final WAL
record that breaks things.
>> We could actually allow the slave to set the visibility map bits based
>> on its own xmin horizon.
> Not in a crash-safe way, which is exactly the problem here.
Brilliant selective quoting.
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