Thread: pgsql-server: Mention that transactions can complete in a different

Log Message:
-----------
Mention that transactions can complete in a different numeric order, for
PITR recovery.

Modified Files:
--------------
    pgsql-server/doc/src/sgml:
        backup.sgml (r2.42 -> r2.43)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/backup.sgml.diff?r1=2.42&r2=2.43)