Data Guard Status

Confirm the database role, protection mode and switchover status for the current Data Guard member.

SELECT
    name,
    db_unique_name,
    database_role,
    open_mode,
    protection_mode,
    protection_level,
    switchover_status
FROM v$database;

Inspect redo transport destination status and the latest applied SCN reported for standby destinations.

SELECT
    dest_id,
    status,
    type,
    database_mode,
    recovery_mode,
    gap_status,
    applied_scn
FROM v$archive_dest_status
WHERE type = 'PHYSICAL'
ORDER BY dest_id;

Check apply lag and transport lag reported by the standby database.

SELECT
    name,
    value,
    unit,
    time_computed,
    datum_time
FROM v$dataguard_stats
WHERE name IN (
    'apply lag',
    'transport lag',
    'apply finish time'
)
ORDER BY name;

Inspect the current Data Guard processes and their actions to understand transport and apply activity.

SELECT
    role,
    thread#,
    sequence#,
    action,
    client_process,
    client_role
FROM v$dataguard_process
ORDER BY
    role,
    thread#,
    sequence#;

Identify archived redo gaps reported by the standby database that may require investigation.

SELECT
    thread#,
    low_sequence#,
    high_sequence#
FROM v$archive_gap
ORDER BY
    thread#,
    low_sequence#;

Find recent Error and Fatal Data Guard messages that were recorded by the database.

SELECT
    timestamp,
    severity,
    facility,
    message
FROM v$dataguard_status
WHERE severity IN ('Error', 'Fatal')
  AND timestamp > SYSDATE - 1
ORDER BY timestamp DESC;