Simon Riggs <simon@2ndquadrant.com> writes:
> On Sun, 2004-11-07 at 11:15, Joachim Wieland wrote:
>> Ok, that seems to be pretty intuitive. But could one extend the recovery
>> mechanism such that one can go from PIT t_0 to PIT t_1 with t_1 > t_0
>> without re-restoring the original backup?
> Same question, just restated.
> When you stop recovery at point in time, t_0 is now in timeline N+1,
> though it does also still exist in timeline N. In the new timeline there
> is no such thing (yet) as a time/transaction > t_0.
The real point is that as soon as you do anything, you are most
definitely not in timeline N anymore; you are executing transactions
in a new history of the database (new timeline). The reason we need
a re-restore is that there's no other way to undo whatever you have
done in timeline N+1.
I suppose it might be useful to have some kind of "suspended animation"
behavior where you could bring up a backend and look at the database in
a strict read-only fashion, not really executing transactions at all,
just to see what you had. Then you could end the recovery and go to
normal operations, or allow the recovery to proceed further if you
decided this wasn't where you wanted to be yet. However that would
require a great deal of mechanism we haven't got (yet). In particular
there is no such thing as strict read-only examination of the database.
regards, tom lane
