/* --- Option A (MySQL ≥5.7 / 8.0): add a per-query timeout hint --- */
/*+ MAX_EXECUTION_TIME(8000) */  -- 8s budget (optional)

SELECT 
  a.id                AS ID,
  a.eventtime         AS StartTimestamp,
  clr.eventtime       AS EndTimestamp,
  CONCAT(
    LPAD(FLOOR(TIMESTAMPDIFF(SECOND, a.eventtime, COALESCE(clr.eventtime, NOW())) / 3600), 2, '0'), ':',
    LPAD(FLOOR((TIMESTAMPDIFF(SECOND, a.eventtime, COALESCE(clr.eventtime, NOW())) % 3600) / 60), 2, '0'), ':',
    LPAD(       (TIMESTAMPDIFF(SECOND, a.eventtime, COALESCE(clr.eventtime, NOW())) % 60)      , 2, '0')
  ) AS Duration,
  CONCAT(REPLACE(a.displaypath, '_', '-'), ' ', SUBSTRING_INDEX(a.source, ':/alm:', -1)) AS Description,
  CASE a.priority
    WHEN 0 THEN 'Diagnostic'
    WHEN 1 THEN 'Low'
    WHEN 2 THEN 'Medium'
    WHEN 3 THEN 'High'
    WHEN 4 THEN 'Critical'
    ELSE 'Unknown'
  END AS Priority,
  SUBSTRING_INDEX(SUBSTRING_INDEX(aed.strValue, '/', 2), '/', -1) AS Location,
  COALESCE(aed.strValue, SUBSTRING_INDEX(a.source, ':/tag:', -1)) AS Tag,
  COALESCE(aed.strValue, a.source) AS FullTag,
  a.displaypath AS Device
FROM alarm_events a
LEFT JOIN alarm_events clr ON (
  clr.eventid = a.eventid 
  AND clr.eventtype = 1 
  AND clr.eventtime >= a.eventtime
  AND clr.eventtime = (
    SELECT MIN(eventtime) 
    FROM alarm_events ae2 
    WHERE ae2.eventid = a.eventid 
      AND ae2.eventtype = 1 
      AND ae2.eventtime >= a.eventtime
  )
)
LEFT JOIN alarm_event_data aed ON (
  aed.id = a.id 
  AND aed.propname = 'myTag'
)
WHERE 
  a.eventtype = 0
  AND a.displaypath NOT LIKE '%System Startup%'
  AND a.source      NOT LIKE '%System Startup%'
  AND (
       (a.eventtime >= :starttime AND a.eventtime < :endtime)
    OR (a.eventtime <  :starttime AND (clr.eventtime IS NULL OR clr.eventtime >= :starttime))
  )
ORDER BY 
  CASE WHEN clr.eventtime IS NULL THEN 0 ELSE 1 END,
  COALESCE(clr.eventtime, a.eventtime) DESC,
  a.id DESC;