Re: Corner case in xlog stuff: what happens exactly at a seg boundary?

I wrote:
> Rather than expecting user-level scripts to get this corner case
> right, I suggest that we ought to modify pg_stop_backup and friends
> so that what they return is the last used byte address of WAL, not
> the first unused byte address as now.  Then, blindly extracting
> the filename will give the right answer about which file to archive,
> even in the boundary case.

After further thought I desisted from that plan: changing the result
convention of existing functions like pg_stop_backup() will break any
existing archiving scripts that do get it right.  Instead, we can put
the boundary-case logic into the new functions that extract a filename
from the WAL location string that the action functions return.
        regards, tom lane