Indexes in Mysql table - mysql

Question

I have such tables:
CREATE TABLE `skadate_newsfeed_action` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`entityId` int(11) NOT NULL,
`entityType` varchar(100) NOT NULL,
`feature` varchar(100) NOT NULL,
`data` longtext NOT NULL,
`status` varchar(20) NOT NULL DEFAULT 'active',
`createTime` int(11) NOT NULL,
`updateTime` int(11) NOT NULL,
`userId` int(11) NOT NULL,
`visibility` int(11) NOT NULL,
`privacy` enum('everybody','friends_only') NOT NULL DEFAULT 'everybody',
PRIMARY KEY (`id`),
KEY `userId` (`userId`),
KEY `privacy` (`visibility`),
KEY `updateTime` (`updateTime`),
KEY `entity` (`entityType`,`entityId`)
) ENGINE=MyISAM;
CREATE TABLE `skadate_profile` (
`profile_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`email` varchar(128) NOT NULL DEFAULT '',
`username` varchar(32) NOT NULL DEFAULT '',
`password` varchar(40) NOT NULL,
`sex` bigint(20) DEFAULT NULL,
`match_sex` bigint(20) DEFAULT NULL,
`birthdate` date NOT NULL DEFAULT '0000-00-00',
`headline` varchar(128) DEFAULT '',
`general_description` text,
`match_agerange` varchar(6) DEFAULT NULL,
`custom_location` varchar(255) DEFAULT NULL,
`country_id` char(2) NOT NULL DEFAULT '',
`zip` varchar(10) DEFAULT NULL,
`state_id` varchar(5) DEFAULT NULL,
`city_id` int(11) DEFAULT '0',
`join_stamp` int(10) unsigned NOT NULL DEFAULT '0',
`activity_stamp` int(10) unsigned NOT NULL DEFAULT '0',
`membership_type_id` int(10) unsigned NOT NULL DEFAULT '18',
`affiliate_id` int(8) unsigned NOT NULL DEFAULT '0',
`email_verified` enum('undefined','yes','no') NOT NULL DEFAULT 'undefined',
`reviewed` enum('n','y') NOT NULL DEFAULT 'n',
`has_photo` enum('n','y') NOT NULL DEFAULT 'n',
`has_media` enum('n','y') NOT NULL DEFAULT 'n',
`status` enum('active','on_hold','suspended') NOT NULL DEFAULT 'active',
`featured` enum('n','y') NOT NULL DEFAULT 'n',
`register_invite_score` tinyint(3) NOT NULL DEFAULT '0',
`rate_score` tinyint(3) unsigned NOT NULL DEFAULT '0',
`rates` bigint(20) unsigned NOT NULL DEFAULT '0',
`language_id` int(10) unsigned NOT NULL DEFAULT '0',
`join_ip` int(11) unsigned NOT NULL DEFAULT '0',
`neigh_location` enum('country','state','city','zip') DEFAULT NULL,
`neigh_location_distance` int(10) unsigned NOT NULL DEFAULT '0',
`bg_color` varchar(32) DEFAULT NULL,
`bg_image` varchar(32) DEFAULT NULL,
`bg_image_url` varchar(255) DEFAULT NULL,
`bg_image_mode` tinyint(1) DEFAULT NULL,
`bg_image_status` enum('active','approval') NOT NULL DEFAULT 'active',
`has_music` enum('n','y') NOT NULL DEFAULT 'n',
`is_private` tinyint(1) NOT NULL DEFAULT '0',
`subscription_id_offerit` text,
PRIMARY KEY (`profile_id`),
UNIQUE KEY `email` (`email`),
UNIQUE KEY `username` (`username`),
KEY `membership_id` (`membership_type_id`),
KEY `zip` (`zip`),
KEY `country_id` (`country_id`),
KEY `state_id` (`state_id`),
KEY `city_id` (`city_id`),
KEY `sex` (`sex`),
KEY `match_sex` (`match_sex`),
KEY `activity_stamp` (`activity_stamp`),
KEY `join_stamp` (`join_stamp`),
KEY `birthdate` (`birthdate`),
KEY `featured` (`featured`,`has_photo`,`activity_stamp`)
) ENGINE=MyISAM;
And try to perform this query:
SELECT DISTINCT `na`.*
FROM `skadate_newsfeed_action` AS `na`
LEFT JOIN `skadate_profile` AS `profile` ON ( `na`.`userId` = `profile`.`profile_id` )
WHERE ( profile.email_verified='yes' OR profile.email_verified='no' OR profile.email_verified='undefined' )
AND `profile`.`status`='active' AND `na`.`status`='active' AND `na`.`privacy`='everybody'
AND `na`.`visibility` & 1 AND `na`.`updateTime` < 1455885224
ORDER BY `na`.`updateTime` DESC, `na`.`id` DESC
LIMIT 0, 10
But when I see EXPLAIN:
Maybe someone can help me, how I can improve this query?

Answer 1

If you want records from only one table, then use exists rather than a join and select distinct. So:
SELECT na.*
FROM `skadate_newsfeed_action` na
WHERE EXISTS (SELECT 1
FROM skadate_profile p
WHERE na.userId = p.profile_id AND
p.email_verified IN ('yes', 'no', 'undefined') AND
p.status = 'active'
) AND
na.status = 'active' AND
na.privacy = 'everybody' AND
na.visibility & 1 > 0 AND
na.updateTime < 1455885224
ORDER BY na.`updateTime` DESC, na.`id` DESC
LIMIT 0, 10;
For this query, you want an index on skadate_profile(profile_id, status, verified). Also, the following index is probably helpful: skadate_newsfeed_action(status, privacy, updateTime, visibility, userId).

Answer 2

This is probably because of the DISTICT keyword. To remove duplicates MySQL needs to sort the result by every selected column.