Re: Rewrite SQL to stop table scan

[Steve Meyers]

On 1/17/11 9:52 AM, Jerry Schwartz wrote:
> [JS] I don't understand how an index on a timestamp would help. Theoretically,
> each record could have a unique value for the timestamp; so the index would
> have an entry for each record. Would MySQL really use that in preference to,
> or in combination with, an index on devid?

You are correct.  The ideal index would be across (devid, stamp).