MySQL查詢優化-提高速度和效率

Question

我想在數據庫中獲取一些電子郵件，每個電子郵件都有一個狀態。 所有可能的狀態都存儲在一個表中，它們都在其中具有權限（例如顯示，編輯，刪除等）。 這些電子郵件不是具有網站權限的用戶，而是用戶已添加的電子郵件列表。

這是表格結構：

電子郵件表格

CREATE TABLE IF NOT EXISTS `email__email` (
    `email_id` int(11) NOT NULL AUTO_INCREMENT,
    `created` timestamp NULL DEFAULT NULL,
    `updated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    `user_fk` int(11) NOT NULL,
    `status_fk` tinyint(2) NOT NULL,
    `language` enum('fr','en') COLLATE utf8_unicode_ci DEFAULT NULL,
    `email` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
    `firstName` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
    `lastName` varchar(100) COLLATE utf8_unicode_ci DEFAULT NULL,
    `companyName` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
    `gender` enum('f','m') COLLATE utf8_unicode_ci DEFAULT NULL,
    PRIMARY KEY (`email_id`),
    UNIQUE KEY `user_email` (`user_fk`,`email`),
    KEY `user_fk` (`user_fk`),
    KEY `created` (`created`),
    KEY `status_fk` (`status_fk`)
    ) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=3031492 ;

狀態表

CREATE TABLE IF NOT EXISTS `email__status` (
    `status_id` int(11) NOT NULL AUTO_INCREMENT,
    `name_fr` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,
    `name_en` varchar(50) COLLATE utf8_unicode_ci DEFAULT NULL,
    `description_fr` varchar(150) COLLATE utf8_unicode_ci DEFAULT NULL,
    `description_en` varchar(150) COLLATE utf8_unicode_ci DEFAULT NULL,
    `permShow` tinyint(1) NOT NULL DEFAULT '0',
    `permSend` tinyint(1) NOT NULL DEFAULT '0',
    `permEdit` tinyint(1) NOT NULL DEFAULT '0',
    `permDelete` tinyint(1) NOT NULL DEFAULT '0',
    `permImport` tinyint(1) NOT NULL DEFAULT '0',
    PRIMARY KEY (`status_id`)
    ) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=7 ;

這是使用EXPLAIN進行的緩慢查詢：

SELECT EE.*, ES.name_fr AS statusName, ES.description_fr AS statusDescription, ES.permShow, ES.permSend, ES.permEdit, ES.permDelete, ES.permImport
    , (SELECT GROUP_CONCAT(CONVERT(CONCAT(GC.name, '~', GC.group_id), CHAR(255)) SEPARATOR ',') FROM `group` GC INNER JOIN group_email GEC ON GEC.group_fk = GC.group_id WHERE GEC.email_fk = EE.email_id AND GC.deleted = 0) AS groups
    FROM `email__email` EE
    INNER JOIN email__status ES ON EE.status_fk = ES.status_id
    WHERE 1 = 1
    AND EE.user_fk = 54
    AND ES.permShow = 1
    ORDER BY EE.email_id DESC LIMIT 15


    EXTRA   ID  KEY KEY_LEN POSSIBLE_KEYS   REF ROWS    SELECT_TYPE TABLE   TYPE
    Using temporary; Using filesort 1   user_email  4   user_email,user_fk,status_fk    const   180681  PRIMARY EE  ref
    Using where; Using join buffer  1   [empty string]  [empty string]  PRIMARY [empty string]  6   PRIMARY ES  ALL
    Using index 2   email_fk    4   group_email,group_fk,email_fk   mailing_dev.EE.email_id 1   DEPENDENT SUBQUERY  GEC ref
    Using where 2   PRIMARY 4   PRIMARY mailing_dev.GEC.group_fk    1   DEPENDENT SUBQUERY  GC  eq_ref

這是使用EXPLAIN的快速查詢：

SELECT EE.*
    , (SELECT GROUP_CONCAT(CONVERT(CONCAT(GC.name, '~', GC.group_id), CHAR(255)) SEPARATOR ',') FROM `group` GC INNER JOIN group_email GEC ON GEC.group_fk = GC.group_id WHERE GEC.email_fk = EE.email_id AND GC.deleted = 0) AS groups
    FROM `email__email` EE
    WHERE 1 = 1 
    AND EE.user_fk = 54
    AND EXISTS(SELECT permShow FROM email__status WHERE status_id = EE.status_fk AND permShow = 1)
    ORDER BY EE.email_id DESC LIMIT 15


    EXTRA   ID  KEY KEY_LEN POSSIBLE_KEYS   REF ROWS    SELECT_TYPE TABLE   TYPE
    Using where 1   PRIMARY 4   user_email,user_fk  [empty string]  270 PRIMARY EE  index
    Using where 3   PRIMARY 4   PRIMARY mailing_dev.EE.status_fk    1   DEPENDENT SUBQUERY  email__status   eq_ref
    Using index 2   email_fk    4   group_email,group_fk,email_fk   mailing_dev.EE.email_id 1   DEPENDENT SUBQUERY  GEC ref
    Using where 2   PRIMARY 4   PRIMARY mailing_dev.GEC.group_fk    1   DEPENDENT SUBQUERY  GC  eq_ref

這兩個查詢之間有很大的區別，但是第二個查詢沒有給我提供我需要獲取的兩個重要列。 我可以執行子查詢以像聯接一樣獲取它們，但仍然，我不想為每個子查詢提供很多子查詢...有什么想法可以改善這一點？

謝謝

Answer 1

email__email.status_fk是tinyint，但是email__status.status_id是int（11）。

這可能會破壞您的INNER JOIN。 更改一種或另一種數據類型，然后重試。