On Wed, Dec 9, 2009 at 12:52 PM, Philip Thompson <philthathril@xxxxxxxxx> 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` always depends on how many records you have, if you have 100-1000 records is very diferent to 100000-500000 > > Thanks, > ~Philip > -- > PHP Database Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > -- Julio Araya C. Linux User #386141 Memorista de Ingeniería Civil Informática Ubuntu User #14778 Universidd Técnica Federico Santa María Valparaíso - Chile -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
