> The recovery mechanism doesn't rely upon you knowing 1 or 3. The
> recovery reads pg_control (from the backup) and then attempts to
> de-archive the appropriate xlog segment file and then starts
> rollforward
Unfortunately this only works if pg_control was the first file to be
backed up (or by chance no checkpoint happened after backup start and
pg_control backup)
Other db's have commands for:
start/end external backup
Maybe we should add those two commands that would initially only do
the following:
start external backup:- (checkpoint as an option)- make a copy of pg_control
end external backup:- record WAL position (helps choose an allowed minimum PIT)
Those commands would actually not be obligatory but recommended, and would
only help with the restore process.
Restore would then eighter take the existing pg_control backup, or ask
the dba where rollforward should start and create a corresponding pg_control.
A helper utility could list possible checkpoints in a given xlog.
Andreas