Re: [HACKERS] Restartable Recovery

Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> I've implemented this for BTree, GIN, GIST using an additional rmgr
> function bool rm_safe_restartpoint(void)
> ...
> "Recovery checkpoints" are now renamed "restartpoints" to avoid
> confusion with checkpoints. So checkpoints occur during normal
> processing (only) and restartpoints occur during recovery (only).

Applied with revisions. As submitted the patch pushed backup_label out
of the way immediately upon reading it, which is no good: you need to be
sure that the starting checkpoint location is written to pg_control
first, else an immediate crash would allow the thing to try to start
from whatever checkpoint is listed in the backed-up pg_control. Also,
the minimum recovery stopping point that's obtained using the label file
still has to be enforced if there's a crash during the replay sequence.
I felt the best way to do that was to copy the minimum stopping point
into pg_control, so that's what the code does now.

Also, as I mentioned earlier, I think that doing restartpoints on the
basis of elapsed time is simpler and more useful than having an explicit
distinction between "normal" and "standby" modes. We can always invent
a standby_mode flag later if we need one, but we don't need it for this.

regards, tom lane