Question

I have a table like this :

CREATE TABLE `hoststatus` (
  `timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `host` varchar(100) NOT NULL,
  `result` tinyint(1) NOT NULL,
  PRIMARY KEY (`timestamp`,`host`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

INSERT INTO `hoststatus` (`timestamp`, `host`, `result`) VALUES
('2012-06-08 14:18:01', 'host1', 0),
('2012-06-08 14:19:01', 'host1', 0),
('2012-06-08 14:20:01', 'host1', 1),
('2012-06-08 14:21:01', 'host1', 1),
('2012-06-08 14:22:01', 'host1', 1),
('2012-06-08 14:23:01', 'host1', 1),
('2012-06-08 14:24:01', 'host1', 0),
('2012-06-08 14:25:01', 'host1', 0),
('2012-06-08 14:26:01', 'host1', 0),
('2012-06-08 14:27:01', 'host1', 0),
('2012-06-08 14:28:01', 'host1', 1),
('2012-06-08 14:29:01', 'host1', 1),
('2012-06-08 14:29:04', 'host2', 0),
('2012-06-08 14:30:01', 'host1', 0),
('2012-06-08 14:30:03', 'host2', 0),
('2012-06-08 14:31:01', 'host1', 0),
('2012-06-08 14:32:01', 'host1', 0),
('2012-06-08 14:32:02', 'host2', 1),
('2012-06-08 14:33:01', 'host1', 0);

This contains connection status of some hosts : 1 means “offline” and 0 is “online”. What I want to deduce using a select request, is the begin and the end timestamps of each “offline” status of each host. In the example above, the request should return something like this :

begin                  end                     host
'2012-06-08 14:20:01'  '2012-06-08 14:23:01'   'host1'
'2012-06-08 14:28:01'  '2012-06-08 14:29:01'   'host1'
'2012-06-08 14:32:02'  '2012-06-08 14:32:02'   'host2'

can someone give me ways to fix this please? Thank you.

Answer 1

You are essentially trying to find “runs” or “streaks” in your data. This answer may provide some guidance for you on how to accomplish your task.

EDIT: The linked answer can be translated to the following for your specific issue:

SELECT
    host,
    MIN(ts) as StartDate, 
    MAX(ts) as EndDate
FROM (
    SELECT
        ts,
        host,
        result,
        (   SELECT
                COUNT(*) 
            FROM
                hoststatus h2 
            WHERE
                h1.host = h2.host
                and h1.result <> h2.result
                and h2.ts >= h1.ts) as rungroup
    FROM
        hoststatus h1) A
WHERE result = 1
GROUP BY host, rungroup
ORDER BY rungroup desc;