On Sun, 2004-11-07 at 11:15, Joachim Wieland wrote: > On Sat, Nov 06, 2004 at 07:17:29PM +0000, Simon Riggs wrote: > > > > Once you have brought up a database in timeline N+1, you can't use it as > > > > the base to recover to a point in timeline N because the data file > > > > contents cannot be trusted to be identical to the way they were in > > > > timeline N. > > > > You mean "in timeline N ... to a point in timeline N+1", don't you? > > > Specifically not. The point is: you can't go back in time. Recovery is a > > rollforward operation, so you must start at an earlier point and > > rollforwards from there. > > 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. In timeline N only, you can go from t_0 to t_1, but not starting from where you are now, because you are now at t_0 in timeline N+1. That's the general case. ...and you can see why Tom described it as like science fiction. Anyway, you're trying to optimize re-recovery, which would be slightly lower on the priority list than optimizing recovery itself. General readers should just remember this: if you recover, and you decide you've done it wrong, you can re-recover to a different place. You don't need to understand all of that complexity to use the PITR facilities. -- Best Regards, Simon Riggs ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
