On Wed, 8 Aug 2001, Jeremy C. Reed wrote:

> On Wed, 8 Aug 2001, Stephen M Jones wrote:
> 
> > to move about 10,000 user accounts and found that the BSD pwd.db/spwd.db
> > concepts were really not practical with a frequently frobbed passwd file.

Look at
http://mail-index.netbsd.org/current-users/2000/07/05/0001.html

And also see PR 7366 patch at
http://www.NetBSD.org/cgi-bin/query-pr-single.pl?number=7366
  "FreeBSD 2.2.8's pwd_mkdb(8) has -u option, which update only one user's
  DB recored.  This imporve perforemanse under many users in the passwd
  file.  I ported this option into NetBSD current, borrows codes from
  FreeBSD."

   Jeremy C. Reed
   http://www.reedmedia.net/