Re: Group by

The only SELECT is on MAX('timestamp'). There is really nothing to Group BY in this query. Dewey Philip Thompson wrote:

Hi. In a mysql query, it is recommended that "GROUP BY" fields be indexed? Using EXPLAIN on one of my queries, I noticed no change between having indexed by GROUP BY field and not indexing it. Any thoughts would be appreciated. In this example, should history_field be indexed...? SELECT MAX(timestamp) AS max_ts FROM history WHERE req_id = 17 AND history_record_id = 35 GROUP BY history_field Thanks, ~Philip