Re: [HACKERS] Point in Time Recovery

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> What is the process of logging to tape? Ideally we could just do 'dd'
> to the tape drive in append mode; however we need a way of signalling
> that we want to change tapes.

The reason we use a user-specifiable shell command for archiving is
so that we do not have to answer the above ;-). It's the user's problem
to write a shell script that does things the way he wants. He can make
it connect to /dev/tty and ask the operator to swap tapes, or whatever.

Personally I am very accustomed to Hewlett-Packard's disk-to-tape backup
program "fbackup", which allows you to provide a shell script to handle
exactly this sort of thing, and it's worked well for me for many years.

> I am asking to make sure we don't need a PITR pause mode that prevents
> WAL files from being archived but also prevents them from being
> recycled.

WAL files will not be recycled until the archiver daemon has set a .done
flag file for them, so I see no problem here. (Note: I took out some
code in Simon's original patch that would start bleating on the basis
of totally unsupportable assumptions about long archival of a log
segment "ought to" take.)

regards, tom lane