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SELECT `timestamp` FROM `events` WHERE `regionID` = ? LIMIT 0,1					

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SELECT 
  `regionID`,
  MAX(`timestamp`)
FROM
  `events`
GROUP BY
  `regionID`					

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select e1.regionID, e1.timestamp, e1.key from events e1
left outer join events e2
on e1.regionID = e2.regionID and e1.timestamp < e2.timestamp
where e2.regionID is null
order by e1.regionID;					

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SELECT
  E.`regionID`,
  E.`timestamp`,
  E.`key`
FROM
  `events` E
WHERE
  `timestamp` = 
    (SELECT 
       MAX(`timestamp`)
     FROM
       `events`
     WHERE
       `regionID` = E.`regionID`)
ORDER BY
  E.`regionID`