Also you may not see a difference because your not even using 'History_field' anywhere in your SELECT statement. I am a little surprised that you didn't receive a error. On Wed, Dec 9, 2009 at 9:31 AM, Juan Pablo Ramirez < ramirez.juanpablo@xxxxxxxxx> wrote: > Hi i recommend always use indexes when programming. developers tend not > to.. and when the databases grows it's difficult to modify or make them > modify the code. > > > > El mié, 09-12-2009 a las 14:22 -0300, Julio Araya escribió: > > 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 > > -- <a href="http://www.c28.com/?adid=st&iid=19467";> <img src="http://www.c28.com/images/banner_88x31.gif"; border="0" width="88" height="31"></a>
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