Excerpts from Steeles's message of vie jul 23 12:36:41 -0400 2010:
> Thanks for the quick reply.
>
> so if I switch target database from recovery mode to normal mode and do
> pg_dump to backup, then switch it back to recovery mode.
The only way to switch back is to have a prior filesystem-level snapshot
before you put it in normal mode, and restore to that snapshot after
pg_dump is complete.