Thread: pgsql: Add a startup check that pg_xlog and pg_xlog/archive_status

Log Message:
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Add a startup check that pg_xlog and pg_xlog/archive_status exist.
If the latter doesn't exist, automatically recreate it.  (We don't do
this for pg_xlog, though, per discussion.)

Jonah Harris

Modified Files:
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    pgsql/doc/src/sgml:
        backup.sgml (r2.120 -> r2.121)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/backup.sgml?r1=2.120&r2=2.121)
    pgsql/src/backend/access/transam:
        xlog.c (r1.321 -> r1.322)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.321&r2=1.322)