How can I optimize this MySQL query to execute fastar? - mysql

Question

this is my query
SELECT * FROM ".TB_PREFIX."wdata
left JOIN ".TB_PREFIX."vdata
ON ".TB_PREFIX."vdata.wref = ".TB_PREFIX."wdata.id
where ".TB_PREFIX."wdata.id = $id
and this is the result of slow query:
Query_time: 0.005000 Lock_time: 0.000000 Rows_sent: 1 Rows_examined: 21184
How can I optimize this code to execute faster?
EDIT:
tables structure:
CREATE TABLE IF NOT EXISTS `tss1_wdata` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`fieldtype` tinyint(2) unsigned NOT NULL,
`oasistype` tinyint(2) unsigned NOT NULL,
`x` smallint(3) NOT NULL,
`y` smallint(3) NOT NULL,
`occupied` tinyint(1) NOT NULL,
`image` char(3) COLLATE utf8_persian_ci NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `id` (`id`),
KEY `id_2` (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=40402 ;
CREATE TABLE IF NOT EXISTS `tss1_vdata` (
`wref` int(11) unsigned NOT NULL,
`owner` int(11) unsigned NOT NULL,
`name` char(100) COLLATE utf8_persian_ci NOT NULL,
`capital` tinyint(1) unsigned NOT NULL,
`pop` mediumint(11) unsigned NOT NULL,
`cp` mediumint(11) unsigned NOT NULL,
`celebration` int(11) NOT NULL DEFAULT '0',
`type` int(11) NOT NULL DEFAULT '0',
`wood` float(12,2) NOT NULL,
`clay` float(12,2) NOT NULL,
`iron` float(12,2) NOT NULL,
`maxstore` int(11) unsigned NOT NULL,
`crop` float(12,2) NOT NULL,
`maxcrop` int(11) unsigned NOT NULL,
`lastupdate` int(11) unsigned NOT NULL,
`loyalty` tinyint(3) NOT NULL DEFAULT '100',
`exp1` int(11) NOT NULL,
`exp2` int(11) NOT NULL,
`exp3` int(11) NOT NULL,
`created` int(11) NOT NULL,
`natar` tinyint(1) unsigned NOT NULL,
`starv` int(11) unsigned NOT NULL,
`starvupdate` int(11) unsigned NOT NULL,
PRIMARY KEY (`wref`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

Answer 1

You are looking for a specific ID, so you can limit the result to 1 row. Also, you can replace wdata.id with the actual id in the ON statement.
SELECT * FROM ".TB_PREFIX."wdata
LEFT JOIN ".TB_PREFIX."vdata
ON ".TB_PREFIX."vdata.wref = '$id'
WHERE ".TB_PREFIX."wdata.id = '$id'
LIMIT 1
You have the right indices, so there's nothing to be done there.

Answer 2

It looks like you have all necessary indexes and query itself is built just right, i.e. there is nothing to improve in SQL. Actually, I would not consider 5ms query as a slow one
If it is critical query executed thousands times a second, you still can cache result on application level or check NoSQL solution. I personally would try to cache it first.

Answer 3

Try to avoid JOIN table, use short and simple query (single) and store results in php array or mysql memory, make sure all the conditions in mysql fields are indexed properly.
May refer mysqlperformanceblog.com for more mysql related articles.