緩慢的mysql查詢多個連接和訂購

我不知道爲什麼這個查詢運行如此緩慢與「訂單」（約15秒）。 ON子句和ORDER BY中的所有字段都有索引。緩慢的mysql查詢多個連接和訂購

SELECT 
    t_prediction.*, 
    t_column.*, 
    t_user.*, 
    t_match.*, 
    t_label.*, 
    t_competition.*, 

    -- COMPETITION_COUNTRY.t_country_id AS t_competition_country_id, 
    COMPETITION_COUNTRY.t_country_confederation_id AS t_competition_country_confederation_id, 
    COMPETITION_COUNTRY.t_country_name AS t_competition_country_name, 
    COMPETITION_COUNTRY.t_country_flag AS t_competition_country_flag, 
    COMPETITION_COUNTRY.t_country_flag_thumbnail AS t_competition_country_flag_thumbnail, 

    -- COMPETITION_COUNTRY_CONFEDERATION.t_confederation_id AS t_competition_country_confederation_id, 
    COMPETITION_COUNTRY_CONFEDERATION.t_confederation_name AS t_competition_country_confederation_name, 
    COMPETITION_COUNTRY_CONFEDERATION.t_confederation_acronym AS t_competition_country_confederation_acronym, 
    COMPETITION_COUNTRY_CONFEDERATION.t_confederation_logo AS t_competition_country_confederation_logo, 
    COMPETITION_COUNTRY_CONFEDERATION.t_confederation_logo_medium AS t_competition_country_confederation_logo_medium, 
    COMPETITION_COUNTRY_CONFEDERATION.t_confederation_logo_thumbnail AS t_competition_country_confederation_logo_thumbnail, 

    HOST_TEAM.t_team_id AS t_host_team_id, 
    HOST_TEAM.t_team_logo AS t_host_team_logo, 
    HOST_TEAM.t_team_logo_medium AS t_host_team_logo_medium, 
    HOST_TEAM.t_team_logo_thumbnail AS t_host_team_logo_thumbnail, 
    HOST_TEAM.t_team_name AS t_host_team_name, 
    HOST_TEAM.t_team_abbr AS t_host_team_abbr, 

    HOST_TEAM_COUNTRY.t_country_id AS t_host_team_country_id, 
    HOST_TEAM_COUNTRY.t_country_confederation_id AS t_host_team_country_confederation_id, 
    HOST_TEAM_COUNTRY.t_country_name AS t_host_team_country_name, 
    HOST_TEAM_COUNTRY.t_country_flag AS t_host_team_country_flag, 
    HOST_TEAM_COUNTRY.t_country_flag_thumbnail AS t_host_team_country_flag_thumbnail, 

    -- HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_id AS t_host_team_country_confederation_id, 
    HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_name AS t_host_team_country_confederation_name, 
    HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_acronym AS t_host_team_country_confederation_acronym, 
    HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_logo AS t_host_team_country_confederation_logo, 
    HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_logo_medium AS t_host_team_country_confederation_logo_medium, 
    HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_logo_thumbnail AS t_host_team_country_confederation_logo_thumbnail, 

    GUEST_TEAM.t_team_id AS t_guest_team_id, 
    GUEST_TEAM.t_team_logo AS t_guest_team_logo, 
    GUEST_TEAM.t_team_logo_medium AS t_guest_team_logo_medium, 
    GUEST_TEAM.t_team_logo_thumbnail AS t_guest_team_logo_thumbnail, 
    GUEST_TEAM.t_team_name AS t_guest_team_name, 
    GUEST_TEAM.t_team_abbr AS t_guest_team_abbr, 

    GUEST_TEAM_COUNTRY.t_country_id AS t_guest_team_country_id, 
    GUEST_TEAM_COUNTRY.t_country_confederation_id AS t_guest_team_country_confederation_id, 
    GUEST_TEAM_COUNTRY.t_country_name AS t_guest_team_country_name, 
    GUEST_TEAM_COUNTRY.t_country_flag AS t_guest_team_country_flag, 
    GUEST_TEAM_COUNTRY.t_country_flag_thumbnail AS t_guest_team_country_flag_thumbnail, 

    -- GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_id AS t_guest_team_country_confederation_id, 
    GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_name AS t_guest_team_country_confederation_name, 
    GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_acronym AS t_guest_team_country_confederation_acronym, 
    GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_logo AS t_guest_team_country_confederation_logo, 
    GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_logo_medium AS t_guest_team_country_confederation_logo_medium, 
    GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_logo_thumbnail AS t_guest_team_country_confederation_logo_thumbnail 

FROM t_prediction 
JOIN t_column ON t_column_id = t_prediction_column_id 
JOIN t_event ON t_event_id = t_column_event_id 
JOIN t_user ON t_user_id = t_column_user_id 
JOIN t_match ON t_match_id = t_prediction_match_id 
LEFT JOIN t_label ON t_match_label_id = t_label_id 
JOIN t_competition ON t_match_competition_id = t_competition_id 

JOIN t_country COMPETITION_COUNTRY 
    ON COMPETITION_COUNTRY.t_country_id = t_competition_country_id 
LEFT JOIN t_confederation COMPETITION_COUNTRY_CONFEDERATION 
    ON t_confederation_id = COMPETITION_COUNTRY.t_country_confederation_id 

JOIN t_team HOST_TEAM 
    ON HOST_TEAM.t_team_id = t_match_host_id 
JOIN t_country HOST_TEAM_COUNTRY 
    ON HOST_TEAM_COUNTRY.t_country_id = HOST_TEAM.t_team_country_id 
LEFT JOIN t_confederation HOST_TEAM_COUNTRY_CONFEDERATION 
    ON HOST_TEAM_COUNTRY_CONFEDERATION.t_confederation_id = HOST_TEAM_COUNTRY.t_country_confederation_id 

JOIN t_team GUEST_TEAM 
    ON GUEST_TEAM.t_team_id = t_match_guest_id 
JOIN t_country GUEST_TEAM_COUNTRY 
    ON GUEST_TEAM_COUNTRY.t_country_id = GUEST_TEAM.t_team_country_id 
LEFT JOIN t_confederation GUEST_TEAM_COUNTRY_CONFEDERATION 
    ON GUEST_TEAM_COUNTRY_CONFEDERATION.t_confederation_id = GUEST_TEAM_COUNTRY.t_country_confederation_id 

ORDER BY t_prediction_datetime DESC

沒有ORDER BY查詢運行在大約0.005秒

任何想法如何解決這個問題呢？

編輯：（表定義）

CREATE TABLE `t_column` (
    `t_column_id` int(10) NOT NULL AUTO_INCREMENT, 
    `t_column_event_id` int(10) NOT NULL, 
    `t_column_user_id` int(10) DEFAULT NULL, 
    `t_column_redeem_datetime` datetime DEFAULT NULL, 
    `t_column_code` varchar(16) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL, 
    `t_column_status` tinyint(1) NOT NULL DEFAULT '0', 
    PRIMARY KEY (`t_column_id`), 
    KEY `t_column_event_id` (`t_column_event_id`), 
    KEY `t_column_user_id` (`t_column_user_id`), 
    KEY `t_column_redeem_datetime` (`t_column_redeem_datetime`), 
    KEY `t_column_code` (`t_column_code`), 
    KEY `t_column_status` (`t_column_status`), 
    KEY `t_column_id` (`t_column_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='Colonne'; 



CREATE TABLE `t_competition` (
    `t_competition_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_competition_name` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    `t_competition_description` text COLLATE utf8_unicode_ci NOT NULL, 
    `t_competition_country_id` int(10) NOT NULL, 
    `t_competition_logo` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_competition_logo_medium` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_competition_logo_thumbnail` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    PRIMARY KEY (`t_competition_id`), 
    KEY `t_competition_id` (`t_competition_id`), 
    KEY `t_competition_country_id` (`t_competition_country_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Competizione (campionato, torneo)'; 

CREATE TABLE `t_confederation` (
    `t_confederation_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_confederation_name` varchar(300) COLLATE utf8_unicode_ci NOT NULL, 
    `t_confederation_acronym` varchar(10) COLLATE utf8_unicode_ci NOT NULL, 
    `t_confederation_logo` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_confederation_logo_medium` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_confederation_logo_thumbnail` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    PRIMARY KEY (`t_confederation_id`), 
    KEY `t_confederation_id` (`t_confederation_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Football Confederations (ie UEFA)'; 

CREATE TABLE `t_country` (
    `t_country_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_country_confederation_id` int(10) NOT NULL, 
    `t_country_name` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    `t_country_flag` varchar(2083) COLLATE utf8_unicode_ci DEFAULT NULL, 
    `t_country_flag_thumbnail` varchar(2083) COLLATE utf8_unicode_ci DEFAULT NULL, 
    PRIMARY KEY (`t_country_id`), 
    KEY `t_country_confederation_id` (`t_country_confederation_id`), 
    KEY `t_country_id` (`t_country_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Paesi'; 

CREATE TABLE `t_event` (
    `t_event_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_event_name` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    `t_event_description` text COLLATE utf8_unicode_ci NOT NULL, 
    `t_event_start_datetime` datetime NOT NULL, 
    `t_event_end_datetime` datetime NOT NULL, 
    `t_event_logo` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_event_logo_medium` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_event_logo_thumbnail` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_event_status` tinyint(2) unsigned NOT NULL DEFAULT '0', 
    PRIMARY KEY (`t_event_id`), 
    KEY `t_event_id` (`t_event_id`), 
    KEY `t_event_start_datetime` (`t_event_start_datetime`), 
    KEY `t_event_end_datetime` (`t_event_end_datetime`), 
    KEY `t_event_status` (`t_event_status`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Eventi (totoamici mondiali, totoamici campionato, totoamici 2015)'; 

CREATE TABLE `t_label` (
    `t_label_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_label_event_id` int(10) unsigned NOT NULL, 
    `t_label_name` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    PRIMARY KEY (`t_label_id`), 
    KEY `t_label_event_id` (`t_label_event_id`), 
    KEY `t_label_id` (`t_label_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE `t_match` (
    `t_match_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_match_event_id` int(10) NOT NULL, 
    `t_match_competition_id` int(10) NOT NULL, 
    `t_match_host_id` int(10) NOT NULL, 
    `t_match_guest_id` int(10) NOT NULL, 
    `t_match_host_score` int(2) DEFAULT NULL, 
    `t_match_guest_score` int(2) DEFAULT NULL, 
    `t_match_datetime` datetime NOT NULL, 
    `t_match_status` int(2) NOT NULL, 
    `t_match_label_id` int(10) NOT NULL, 
    PRIMARY KEY (`t_match_id`), 
    KEY `t_match_event_id` (`t_match_event_id`), 
    KEY `t_match_competition_id` (`t_match_competition_id`), 
    KEY `t_match_host_id` (`t_match_host_id`), 
    KEY `t_match_guest_id` (`t_match_guest_id`), 
    KEY `t_match_datetime` (`t_match_datetime`), 
    KEY `t_match_label_id` (`t_match_label_id`), 
    KEY `t_match_status` (`t_match_status`), 
    KEY `t_match_id` (`t_match_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Incontri'; 

CREATE TABLE `t_prediction` (
    `t_prediction_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_prediction_match_id` int(10) unsigned NOT NULL, 
    `t_prediction_column_id` int(10) NOT NULL, 
    `t_prediction_datetime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, 
    `t_prediction_value` varchar(1) COLLATE utf8_unicode_ci NOT NULL, 
    PRIMARY KEY (`t_prediction_id`), 
    KEY `t_prediction_id` (`t_prediction_id`), 
    KEY `t_prediction_match_id` (`t_prediction_match_id`), 
    KEY `t_prediction_column_id` (`t_prediction_column_id`), 
    KEY `t_prediction_datetime` (`t_prediction_datetime`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='1, X, 2'; 

CREATE TABLE `t_team` (
    `t_team_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_team_logo` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_team_logo_medium` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_team_logo_thumbnail` varchar(2083) COLLATE utf8_unicode_ci NOT NULL, 
    `t_team_country_id` int(10) NOT NULL, 
    `t_team_name` varchar(40) COLLATE utf8_unicode_ci NOT NULL, 
    `t_team_abbr` varchar(5) COLLATE utf8_unicode_ci NOT NULL, 
    PRIMARY KEY (`t_team_id`), 
    KEY `t_team_id` (`t_team_id`), 
    KEY `t_team_country_id` (`t_team_country_id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Squadre'; 

CREATE TABLE `t_user` (
    `t_user_id` int(10) unsigned NOT NULL AUTO_INCREMENT, 
    `t_user_confirmed` tinyint(1) NOT NULL DEFAULT '0', 
    `t_user_first_name` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    `t_user_last_name` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    `t_user_email` varchar(300) COLLATE utf8_unicode_ci NOT NULL, 
    `t_user_password` varchar(300) COLLATE utf8_unicode_ci NOT NULL, 
    `t_user_salt` varchar(8) COLLATE utf8_unicode_ci NOT NULL, 
    `t_user_team_id` int(10) NOT NULL, 
    `t_user_photo` varchar(2083) COLLATE utf8_unicode_ci DEFAULT NULL, 
    `t_user_photo_medium` varchar(2083) COLLATE utf8_unicode_ci DEFAULT NULL, 
    `t_user_photo_thumbnail` varchar(2083) COLLATE utf8_unicode_ci DEFAULT NULL, 
    `t_user_confirmation_code` varchar(100) COLLATE utf8_unicode_ci NOT NULL, 
    `t_user_datetime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, 
    PRIMARY KEY (`t_user_id`), 
    UNIQUE KEY `t_user_email_2` (`t_user_email`), 
    KEY `t_user_id` (`t_user_id`), 
    KEY `t_user_email` (`t_user_email`), 
    KEY `t_user_team_id` (`t_user_team_id`), 
    KEY `t_user_datetime` (`t_user_datetime`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci COMMENT='Utenti'; 
DROP TABLE IF EXISTS `t_prediction_full`;

來源

2014-06-29 razorxan

沒有模式和執行計劃（'EXPLAIN'是你的朋友），我們無能爲力。 – jcaron

你需要什麼？查詢和表結構的解釋？ – razorxan

您使用子查詢的方式是一個壞主意。首先刪除僅引用一個表的所有子查詢。

因此，而不是：

JOIN (
SELECT 
    t_team_id AS t_guest_team_id, 
    t_team_logo AS t_guest_team_logo, 
    t_team_logo_medium AS t_guest_team_logo_medium, 
    t_team_logo_thumbnail AS t_guest_team_logo_thumbnail, 
    t_team_country_id AS t_guest_team_country_id, 
    t_team_name AS t_guest_team_name, 
    t_team_abbr AS t_guest_team_abbr 
FROM 
    t_team 
) G

只要做到：

JOIN t_team G

然後參考使用G列。

當您使用子查詢時，MySQL實際上會創建派生表。這是不必要的開銷。 Plus MySQL失去了在結果上使用索引的能力。

來源

2014-06-29 15:40:53

爲什麼我使用子查詢的原因是因爲否則我不能再引用字段了，因爲他們的名字在結果中重複（php PDO fetch_assoc）。 – razorxan

使用'table.field as table_field'來解決重複的問題 –

我不知道你在說什麼。你能解釋一下嗎？預先感謝你 – razorxan

緩慢的mysql查詢多個連接和訂購

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