Re: BUG #15964: vacuumdb.c:187:10: error: use of undeclared identifier 'FD_SETSIZE'

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> I guess the other possibility is that there exists an operating system
> that returns file descriptors higher than its FD_SETSIZE, when some fds
> below FD_SETSIZE are still available.  Doesn't seem realistic.

I think POSIX requires open() to select the lowest unused FD.  Otherwise
tricks like closing and reopening stdout wouldn't work reliably.

            regards, tom lane