Re: Group by

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@gmail.com> 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 >