为什么添加额外的 'OR' 使得针对 MYSQL 视图的查询非常慢

Question

我的 SQL 查询如下所示：

SELECT * FROM `userListView` `t` 
WHERE (((((((email LIKE '%western millwork%') OR 
(firstName LIKE '%western millwork%')) OR 
(lastName LIKE '%western millwork%')) OR 
(name LIKE '%western millwork%')) OR 
(company LIKE '%western millwork%')) OR 
(companyName LIKE '%western millwork%')) OR 
(visualId LIKE '%western millwork%')) 
AND (active='1') 
ORDER BY `t`.`lastName`, `t`.`firstName` LIMIT 30

查询运行很好，直到我添加了关于 'companyName'.

的行

一旦发生这种情况，它就会从大约 1 秒变成 15 - 20 秒。

我认为这与视图的创建方式有关？所以有 'company'.'name' 然后 'userListView' 中有 'companyName' 这就是我要查询的内容。

创建视图的方式如下：

CREATE 
    ALGORITHM = UNDEFINED 
    DEFINER = `3form`@`192.168.%.%` 
    SQL SECURITY DEFINER
VIEW `userListView` AS
    (SELECT 
        `user`.`uid` AS `uid`,
        `user`.`active` AS `active`,
        `user`.`email` AS `email`,
        `user`.`fname` AS `firstName`,
        `user`.`lname` AS `lastName`,
        CONCAT(`user`.`fname`, ' ', `user`.`lname`) AS `name`,
        `user`.`company` AS `company`,
        `user`.`cust_id` AS `visualId`,
        `user`.`repid` AS `repId`,
        `user`.`srepid` AS `studioRepId`,
        `user`.`lightartrepid` AS `lightArtRepId`,
        `user`.`exteriorrepid` AS `exteriorRepId`,
        `user`.`nationalrepid` AS `nationalRepId`,
        `user`.`phone` AS `phone`,
        `user`.`phone_ext` AS `phoneExt`,
        `user`.`fax` AS `fax`,
        `user`.`mobile` AS `mobile`,
        `billingAddress`.`label` AS `billingAddressLabel`,
        `billingAddress`.`addr` AS `billingAddressAddr`,
        `billingAddress`.`addr2` AS `billingAddressAddr2`,
        `billingAddress`.`city` AS `billingAddressCity`,
        `billingAddress`.`state` AS `billingAddressState`,
        `billingAddress`.`zip` AS `billingAddressZip`,
        `billingAddress`.`country` AS `billingAddressCountry`,
        `shippingAddress`.`label` AS `shippingAddressLabel`,
        `shippingAddress`.`addr` AS `shippingAddressAddr`,
        `shippingAddress`.`addr2` AS `shippingAddressAddr2`,
        `shippingAddress`.`city` AS `shippingAddressCity`,
        `shippingAddress`.`state` AS `shippingAddressState`,
        `shippingAddress`.`zip` AS `shippingAddressZip`,
        `shippingAddress`.`country` AS `shippingAddressCountry`,
        `branch`.`bid` AS `bid`,
        `branch`.`description` AS `branchDescription`,
        `branch`.`repid` AS `branchRepId`,
        `branch`.`studiorepid` AS `branchStudioRepId`,
        `branch`.`lightartrepid` AS `branchLightArtRepId`,
        `branch`.`exteriorrepid` AS `branchExteriorRepId`,
        `branch`.`nationalrepid` AS `branchNationalRepId`,
        `branchAddress`.`label` AS `branchAddressLabel`,
        `branchAddress`.`addr` AS `branchAddressAddr`,
        `branchAddress`.`addr2` AS `branchAddressAddr2`,
        `branchAddress`.`city` AS `branchAddressCity`,
        `branchAddress`.`state` AS `branchAddressState`,
        `branchAddress`.`zip` AS `branchAddressZip`,
        `branchAddress`.`country` AS `branchAddressCountry`,
        `company`.`cid` AS `cid`,
        `company`.`name` AS `companyName`,
        `company`.`url` AS `companyUrl`,
        `company`.`visual_id` AS `companyVisualId`,
        `company`.`phone` AS `companyPhone`,
        `company`.`fax` AS `companyFax`,
        `companyAddress`.`label` AS `companyAddressLabel`,
        `companyAddress`.`addr` AS `companyAddressAddr`,
        `companyAddress`.`addr2` AS `companyAddressAddr2`,
        `companyAddress`.`city` AS `companyAddressCity`,
        `companyAddress`.`state` AS `companyAddressState`,
        `companyAddress`.`zip` AS `companyAddressZip`,
        `companyAddress`.`country` AS `companyAddressCountry`
    FROM
        ((((((`users` `user`
        LEFT JOIN `useraddr` `billingAddress` ON (((`user`.`uid` = `billingAddress`.`uid`)
            AND (`user`.`billaddr` = (`billingAddress`.`label` COLLATE utf8_unicode_ci)))))
        LEFT JOIN `useraddr` `shippingAddress` ON (((`user`.`uid` = `shippingAddress`.`uid`)
            AND (`user`.`billaddr` = (`shippingAddress`.`label` COLLATE utf8_unicode_ci)))))
        LEFT JOIN `branch` ON ((`user`.`bid` = `branch`.`bid`)))
        LEFT JOIN `branch_address` `branchAddress` ON (((`branch`.`bid` = `branchAddress`.`bid`)
            AND (`branch`.`shipto` = (`branchAddress`.`label` COLLATE utf8_unicode_ci)))))
        LEFT JOIN `company` ON ((`company`.`cid` = `branch`.`cid`)))
        LEFT JOIN `company_address` `companyAddress` ON (((`company`.`cid` = `companyAddress`.`cid`)
            AND (`company`.`billto` = (`companyAddress`.`label` COLLATE utf8_unicode_ci))))))

想法是 'companyName' 会优先于 'company'，但这还没有发生。因此，为什么原始查询同时查看两者。

知道问题出在哪里吗？

更新:

解释如下：

Answer 1

由于多种原因，此查询及其基础视图可能很慢。

column LIKE '%value%' 是减慢查询速度的最有效方法。它必须检查列中的每个值，并且不能利用任何索引查找。如果您可以将这些项目的部分或全部更改为 column LIKE 'value%'，您将会看到改进。
OR 子句，尤其是与 LIKE '%value%' 结合使用时，查询速度也很慢。有时查询规划器必须对结果集进行多次传递。
您已将 OR 子句用括号分组，这告诉查询计划器您不信任它来决定 OR 子句链的哪些部分最有可能是最快的。去掉所有那些嵌套的括号。
您正在对 CONCAT() 操作的结果进行 LIKE 搜索。这保证了查询规划器无法优化上述问题。
MySQL 没有物化视图。每次使用时都会重建视图。 MySQL 中的视图主要用于清晰度，而不是性能。
SELECT * FROM ... ORDER BY something LIMIT small-number 是复杂查询中的经典反模式。它执行整个查询，然后对其进行排序，然后丢弃大部分。
您在 JOIN ... ON 子句上使用了 COLLATE 修饰符。如果这些是必要的，那么您就无法在 ON 条件下使用索引：排序规则被嵌入到 MySQL 索引中。如果您的 COLLATE 子句覆盖默认排序规则，则无法使用索引。
但显着放缓的 'real' 问题更为隐蔽。起初，您过滤一个 table (users)。当您添加 companyName 时，它不需要同时过滤 VIEW 中的另一个 table。这意味着它必须保留第一个 table 的所有行，以防 companyName 匹配。解决方法是将 that OR 变成 UNION.
此处列出的许多问题没有简单的加速。

在尝试解决此问题时，您可能需要将 SQL_NO_CACHE 添加到 select 语句中，如下所示

  SELECT SQL_NO_CACHE whatever FROM whatever

那是因为 MySQL 检测到重复的查询，并且 returns 如果可以（并且 "Query cache" 已打开），先前的结果会很快（亚秒级）。

这种广角站内搜索，大概应该对每一大类数据分别处理。例如，您需要执行单独的单个 table 查询以从 user 和 company table 中提取相关的 id 值，然后弄清楚如何获取相关数据。

为什么添加额外的 'OR' 使得针对 MYSQL 视图的查询非常慢

Why is adding an extra 'OR' making a query against a MYSQL View very slow

mysql

query-performance