On 01/14/2011 08:19 AM, Steve Meyers wrote: > On 1/14/11 3:52 AM, Bruce Ferrell wrote: >> select count(*) as count >> from alerts where (unix_timestamp(stamp)> (unix_timestamp(now()) - >> '300' ) ) >> and devid = '244'; >> > > Bruce - > > The problem is that the index is useless, because you're running a > function on the timestamp. What you want is this: > > SELECT COUNT(*) AS num FROM alerts WHERE stamp > DATE_SUB(NOW(), > interval 300 second) AND devid=244; > > With this query, MySQL will run DATE_SUB() once, and then use the > index on stamp (which I assume you have) to narrow down the result set. > > Steve > That did it! Thank you.
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