我应该在MySQL表中的何处放置索引
我有以下三个我应该在MySQL表中的何处放置索引,mysql,database,database-design,indexing,Mysql,Database,Database Design,Indexing,我有以下三个WHERE子句: WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight != $maxImageHeight WHERE primaryId = $imgId AND imgWidth != $maxImageWidth AN
WHERE
子句:
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight != $maxImageHeight
WHERE primaryId = $imgId AND imgWidth != $maxImageWidth AND imgHeight = $maxImageHeight"
SELECT 'allEqual' AS COL1,COUNT(*) AS imgCount FROM (
SELECT imgHeight, imgWidth, imgId AS primaryId FROM primary_images
UNION ALL
SELECT imgHeight, imgWidth, primaryId FROM secondary_images
) AS union_table
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`primary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`imgTitle` VARCHAR(255) NULL DEFAULT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`secondary` ENUM('true','false') NOT NULL DEFAULT false ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
`imgClass` ENUM('Jeans','T-Shirts','Shoes','Dress Shirts','Trackwear & Sweatwear') NULL DEFAULT NULL ,
`imgFamily` ENUM('Hugo Boss','Lacoste','True Religion','7 For All Mankind','Robin\'s Jeans','Robert Graham') NULL DEFAULT NULL ,
`imgGender` ENUM('Men\'s','Women\'s') NOT NULL DEFAULT Mens ,
PRIMARY KEY (`imgId`) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) )
ENGINE = InnoDB;
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`secondary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`primaryId` SMALLINT(6) UNSIGNED NOT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
PRIMARY KEY (`imgId`, `primaryId`) ,
INDEX `fk_secondary_images_primary_images` (`primaryId` ASC) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) ,
CONSTRAINT `fk_secondary_images_primary_images`
FOREIGN KEY (`primaryId` )
REFERENCES `new_arrivals_images`.`primary_images` (`imgId` )
ON DELETE CASCADE
ON UPDATE CASCADE)
ENGINE = InnoDB;
它们作用于在查询中使用UNION ALL
连接的两个MySQL InnoDB表
我不知道如何在这两个表中设置索引;我是否应该有一个包含imgWidth
和imgHeight
的多列索引,或者它是否也应该包含primaryId
一个查询只能使用一个索引是真的吗?如果没有,我可以将每列设置为索引吗
或者多列索引在这种情况下不起作用
这里是第一个
WHERE
子句的完整查询示例。其他条款相同,各条款如下:
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight != $maxImageHeight
WHERE primaryId = $imgId AND imgWidth != $maxImageWidth AND imgHeight = $maxImageHeight"
SELECT 'allEqual' AS COL1,COUNT(*) AS imgCount FROM (
SELECT imgHeight, imgWidth, imgId AS primaryId FROM primary_images
UNION ALL
SELECT imgHeight, imgWidth, primaryId FROM secondary_images
) AS union_table
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`primary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`imgTitle` VARCHAR(255) NULL DEFAULT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`secondary` ENUM('true','false') NOT NULL DEFAULT false ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
`imgClass` ENUM('Jeans','T-Shirts','Shoes','Dress Shirts','Trackwear & Sweatwear') NULL DEFAULT NULL ,
`imgFamily` ENUM('Hugo Boss','Lacoste','True Religion','7 For All Mankind','Robin\'s Jeans','Robert Graham') NULL DEFAULT NULL ,
`imgGender` ENUM('Men\'s','Women\'s') NOT NULL DEFAULT Mens ,
PRIMARY KEY (`imgId`) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) )
ENGINE = InnoDB;
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`secondary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`primaryId` SMALLINT(6) UNSIGNED NOT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
PRIMARY KEY (`imgId`, `primaryId`) ,
INDEX `fk_secondary_images_primary_images` (`primaryId` ASC) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) ,
CONSTRAINT `fk_secondary_images_primary_images`
FOREIGN KEY (`primaryId` )
REFERENCES `new_arrivals_images`.`primary_images` (`imgId` )
ON DELETE CASCADE
ON UPDATE CASCADE)
ENGINE = InnoDB;
以下是主图像的模式:
表:
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight != $maxImageHeight
WHERE primaryId = $imgId AND imgWidth != $maxImageWidth AND imgHeight = $maxImageHeight"
SELECT 'allEqual' AS COL1,COUNT(*) AS imgCount FROM (
SELECT imgHeight, imgWidth, imgId AS primaryId FROM primary_images
UNION ALL
SELECT imgHeight, imgWidth, primaryId FROM secondary_images
) AS union_table
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`primary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`imgTitle` VARCHAR(255) NULL DEFAULT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`secondary` ENUM('true','false') NOT NULL DEFAULT false ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
`imgClass` ENUM('Jeans','T-Shirts','Shoes','Dress Shirts','Trackwear & Sweatwear') NULL DEFAULT NULL ,
`imgFamily` ENUM('Hugo Boss','Lacoste','True Religion','7 For All Mankind','Robin\'s Jeans','Robert Graham') NULL DEFAULT NULL ,
`imgGender` ENUM('Men\'s','Women\'s') NOT NULL DEFAULT Mens ,
PRIMARY KEY (`imgId`) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) )
ENGINE = InnoDB;
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`secondary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`primaryId` SMALLINT(6) UNSIGNED NOT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
PRIMARY KEY (`imgId`, `primaryId`) ,
INDEX `fk_secondary_images_primary_images` (`primaryId` ASC) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) ,
CONSTRAINT `fk_secondary_images_primary_images`
FOREIGN KEY (`primaryId` )
REFERENCES `new_arrivals_images`.`primary_images` (`imgId` )
ON DELETE CASCADE
ON UPDATE CASCADE)
ENGINE = InnoDB;
和次映像的架构表:
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight != $maxImageHeight
WHERE primaryId = $imgId AND imgWidth != $maxImageWidth AND imgHeight = $maxImageHeight"
SELECT 'allEqual' AS COL1,COUNT(*) AS imgCount FROM (
SELECT imgHeight, imgWidth, imgId AS primaryId FROM primary_images
UNION ALL
SELECT imgHeight, imgWidth, primaryId FROM secondary_images
) AS union_table
WHERE primaryId = $imgId AND imgWidth = $maxImageWidth AND imgHeight = $maxImageHeight
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`primary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`imgTitle` VARCHAR(255) NULL DEFAULT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`secondary` ENUM('true','false') NOT NULL DEFAULT false ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
`imgClass` ENUM('Jeans','T-Shirts','Shoes','Dress Shirts','Trackwear & Sweatwear') NULL DEFAULT NULL ,
`imgFamily` ENUM('Hugo Boss','Lacoste','True Religion','7 For All Mankind','Robin\'s Jeans','Robert Graham') NULL DEFAULT NULL ,
`imgGender` ENUM('Men\'s','Women\'s') NOT NULL DEFAULT Mens ,
PRIMARY KEY (`imgId`) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) )
ENGINE = InnoDB;
CREATE TABLE IF NOT EXISTS `new_arrivals_images`.`secondary_images` (
`imgId` SMALLINT(6) UNSIGNED NOT NULL AUTO_INCREMENT ,
`primaryId` SMALLINT(6) UNSIGNED NOT NULL ,
`view` VARCHAR(45) NULL DEFAULT NULL ,
`imgURL` VARCHAR(255) NULL DEFAULT NULL ,
`imgWidth` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgHeight` SMALLINT(6) UNSIGNED NULL DEFAULT NULL ,
`imgDate` DATETIME NULL DEFAULT NULL ,
PRIMARY KEY (`imgId`, `primaryId`) ,
INDEX `fk_secondary_images_primary_images` (`primaryId` ASC) ,
UNIQUE INDEX `imgDate_UNIQUE` (`imgDate` DESC) ,
CONSTRAINT `fk_secondary_images_primary_images`
FOREIGN KEY (`primaryId` )
REFERENCES `new_arrivals_images`.`primary_images` (`imgId` )
ON DELETE CASCADE
ON UPDATE CASCADE)
ENGINE = InnoDB;
primaryId列是否有重复项?或者它是主键?如果它是一个主键,那么它也将作为一个精细的索引。在InnoDB中,如果它是主键,那么它可能已经是索引了 换句话说,WHERE子句的区别有多大?如果它通常不匹配,或者正好匹配一行,或者只匹配几行,那么另一个索引将不会有多大帮助。如果它匹配数百行或数千行,另一个索引可能会很有帮助 查询肯定可以使用多个索引 这是一个大问题是“你想做什么?”的案例,看起来你想选择一个维度与输入匹配的图像 考虑通过重做逻辑并去掉UNIONALL子句(它会变成三个查询)来提高效率
primaryId列是否有重复项?或者它是主键?如果它是一个主键,那么它也将作为一个精细的索引。在InnoDB中,如果它是主键,那么它可能已经是索引了 换句话说,WHERE子句的区别有多大?如果它通常不匹配,或者正好匹配一行,或者只匹配几行,那么另一个索引将不会有多大帮助。如果它匹配数百行或数千行,另一个索引可能会很有帮助 查询肯定可以使用多个索引 这是一个大问题是“你想做什么?”的案例,看起来你想选择一个维度与输入匹配的图像 考虑通过重做逻辑并去掉UNIONALL子句(它会变成三个查询)来提高效率 一个查询只能使用一个索引是真的吗 不,那太傻了 如果没有,我可以将每列设置为索引吗 是的,这是一个选项,但仅当您独立使用该列时。
如果您总是像在这里一样合并字段,那么使用复合索引会更有效 我不知道如何在这两个表中设置索引;我是应该有一个包含imgWidth和imgHeight的多列索引,还是应该包含primaryId 如果需要,可以使用复合索引组合
(imgWidth,imgHeight)
但是,您必须记住,如果不在
where
子句中使用imgWidth
,就无法访问imgHeight
上的索引。必须始终使用复合索引的最左侧部分(或全部) 在InnoDB上,主键总是包含在每个辅助索引中,因此包含主键会适得其反 增加了InnoDB的奖金
如果只选择索引字段,InnoDB将永远不会实际读取tabledata,因为所需的所有数据都在索引中。这将大大加快速度 您有一个SQL注入漏洞
您的代码似乎有SQL注入漏洞。请用单引号将所有$var括起来:
where field1='$var'…
,不要忘记使用$var=mysql\u real\u escape\u字符串($var)将它们注入查询之前,请执行代码>操作。见:
为了速度和安全,查询内容应为:
SELECT 'allEqual' AS COL1, COUNT(*) AS imgCount FROM (
SELECT imgId AS primaryId FROM primary_images pi
WHERE pi.ImgId = '$imgId'
AND pi.imgWidth = '$maxImageWidth'
AND pi.imgHeight = '$maxImageHeight'
UNION ALL
SELECT primaryId FROM secondary_images si
WHERE si.primaryId = '$imgId'
AND si.imgWidth = '$maxImageWidth'
AND si.imgHeight = '$maxImageHeight'
) AS union_table
这样,将使用适当的索引,并且不会检索到不需要的数据。
MySQL无法对联合数据使用索引,因为它是两个不同表的合并。这就是为什么需要在内部选择中执行where
一个查询只能使用一个索引是真的吗
不,那太傻了
如果没有,我可以将每列设置为索引吗
是的,这是一个选项,但仅当您独立使用该列时。
如果您总是像在这里一样合并字段,那么使用复合索引会更有效
我不知道如何在这两个表中设置索引;我是应该有一个包含imgWidth和imgHeight的多列索引,还是应该包含primaryId
如果需要,可以使用复合索引组合(imgWidth,imgHeight)
但是,您必须记住,如果不在where
子句中使用imgWidth
,就无法访问imgHeight
上的索引。
必须始终使用复合索引的最左侧部分(或全部)
在InnoDB上,主键总是包含在每个辅助索引中,因此包含主键会适得其反
增加了InnoDB的奖金
如果只选择索引字段,InnoDB将永远不会实际读取tabledata,因为所需的所有数据都在索引中。这将大大加快速度
您有一个SQL注入漏洞
您的代码似乎有SQL注入漏洞。请用单引号将所有$var括起来:where field1='$var'…
,不要忘记使用$var=mysql\u real\u escape\u字符串($var)代码>在注入t之前