Jônatas Zechim wrote: > For example i’ve this query: > > > > SELECT admin_nome FROM ctalk_admin WHERE admin_lastping <= '1233762658' AND > admin_lastping >= '1233762608' AND admin_id='1' > > > > I ran explain, the result for extra is ‘Impossible WHERE noticed after > reading const table...’ > > How can i optimize this query? > > Is there some tutorial on the net? > I am going to guess that that admin_id column is already your primary key and therefor is unique and indexed by default. I would add a compound index to ctalk_admin ALTER TABLE `ctalk_admin` ADD INDEX (`admin_id`, `admin_lastping`) or something along that line. > > > Thanks, > > Zechim > > > > De: Bastien Koert [mailto:phpster@xxxxxxxxx] > Enviada em: quarta-feira, 4 de fevereiro de 2009 12:46 > Para: Jônatas Zechim > Cc: php-general@xxxxxxxxxxxxx > Assunto: Re: Mutiple SQL request > > > > > > On Wed, Feb 4, 2009 at 9:43 AM, Jônatas Zechim <zechim.php@xxxxxxxxx> wrote: > > Hi there, i've a system that do a query each 3s, does it impact on mysql > Server? > I mean, can this slow my Server? > > zechim > > > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > > It impacts system recources if this same query is run constantly for each > user. Example: if this runs a logon and you have 100 or 1000 users logging > on at roughly the same time, then you will have contention for the > resources. > > Can you check your indeces and run explain plans on the queries to see if > any of them can be optimised to run quicker? > -- Jim Lucas "Some men are born to greatness, some achieve greatness, and some have greatness thrust upon them." Twelfth Night, Act II, Scene V by William Shakespeare -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
