Log Message:
-----------
Add a note that pg_start_backup will take awhile because of new
distributed checkpoint behavior. Explain how to work around this
by issuing a manual CHECKPOINT command. Per discussion with Heikki.
Modified Files:
--------------
pgsql/doc/src/sgml:
backup.sgml (r2.97 -> r2.98)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/backup.sgml.diff?r1=2.97&r2=2.98)