How to stop managed recovery (MRP) on an Oracle Data Guard standby

Cancel MRP so the standby stops applying redo. Needed before switchover, before opening the standby read/write (snapshot standby), or before patching. Once stopped, the standby keeps receiving redo (RFS is untouched) but does not apply it.

Run on the standby only. While MRP is stopped, apply lag grows — restart it as soon as the reason for stopping is done. Verify with V$MANAGED_STANDBY: MRP0 should be absent afterwards.

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

-- Verify (read-only) — MRP0 should be gone
SELECT process, status, thread#, sequence#
FROM   v$managed_standby
WHERE  process IN ('MRP0', 'MRP');