我们有以下 mysql 表(简化为直接进入重点)

CREATE TABLE `MONTH_RAW_EVENTS` (
  `idEvent` int(11) unsigned NOT NULL,
  `city` varchar(45) NOT NULL,
  `country` varchar(45) NOT NULL,
  `ts` datetime NOT NULL,
  `idClient` varchar(45) NOT NULL,
  `event_category` varchar(45) NOT NULL,
  ... bunch of other fields
  PRIMARY KEY (`idEvent`),
  KEY `idx_city` (`city`),
  KEY `idx_country` (`country`),
  KEY `idClient` (`idClient`),
) ENGINE=InnoDB;

CREATE TABLE `compilation_table` (
  `idClient` int(11) unsigned DEFAULT NULL,
  `city` varchar(200) DEFAULT NULL,
  `month` int(2) DEFAULT NULL,
  `year` int(4) DEFAULT NULL,
  `events_profile` int(10) unsigned NOT NULL DEFAULT '0',
  `events_others` int(10) unsigned NOT NULL DEFAULT '0',
  `events_total` int(10) unsigned NOT NULL DEFAULT '0',
  KEY `idx_month` (`month`),
  KEY `idx_year` (`year`),
  KEY `idx_idClient` (`idClient`),
  KEY `idx_city` (`city`)
) ENGINE=InnoDB;
MONTH_RAW_EVENTS 包含近 2000 万行用户在网站中执行的操作,大小接近 4GB
compilation_table 每个月都有一个客户/城市摘要,我们用它来实时显示网站上的统计数据

我们每月处理一次统计信息(从第一个表到第二个),并且我们正在尝试优化执行此类操作的查询(因为到目前为止,我们正在处理需要很长时间的 PHP 中的所有内容)

这是我们提出的查询,它在使用小数据子集时似乎可以完成工作,
处理全套数据需要6个多小时的问题
INSERT INTO compilation_table (idClient,city,month,year,events_profile,events_others)


    SELECT  IFNULL(OTHERS.idClient,AP.idClient) as idClient,
            IF(IFNULL(OTHERS.city,AP.city)='','Others',IFNULL(OTHERS.city,AP.city)) as city,
        01,2014,
    IFNULL(AP.cnt,0) as events_profile,
        IFNULL(OTHERS.cnt,0) as events_others

    FROM
    (
        SELECT idClient,CONCAT(city,', ',country) as city,count(*) as cnt
        FROM `MONTH_RAW_EVENTS` WHERE `ts`>'2014-01-01 00:00:00' AND `ts`<='2014-01-31 23:59:59'
        AND `event_category`!='CLIENT PROFILE'
        GROUP BY idClient,city
    ) as OTHERS
 LEFT JOIN
    (
        SELECT idClient,CONCAT(city,', ',country) as city,count(*) as cnt
        FROM `MONTH_RAW_EVENTS` WHERE `ts`>'2014-01-01 00:00:00' AND `ts`<='2014-01-31 23:59:59'
        AND `event_category`='CLIENT PROFILE'
        GROUP BY idClient,city
    ) as CLIPROFILE
    ON CLIPROFILE.city=OTHERS.city and CLIPROFILE.idClient=OTHERS.idClient

 UNION

    SELECT  IFNULL(OTHERS.idClient,CLIPROFILE.idClient) as idClient,
            IF(IFNULL(OTHERS.city,CLIPROFILE.city)='','Others',IFNULL(OTHERS.city,CLIPROFILE.city)) as city,
            01,2014,
            IFNULL(CLIPROFILE.cnt,0) as events_profile,
            IFNULL(OTHERS.cnt,0) as events_others
    FROM
    (
        SELECT idClient,CONCAT(city,', ',country) as city,count(*) as cnt
        FROM `MONTH_RAW_EVENTS` WHERE `ts`>'2014-01-01 00:00:00' AND `ts`<='2014-01-31 23:59:59'
        AND `event_category`!='CLIENT PROFILE'
        GROUP BY idClient,city
    ) as OTHERS
 RIGHT JOIN
    (
        SELECT idClient,CONCAT(city,', ',country) as city,count(*) as cnt
        FROM `MONTH_RAW_EVENTS` WHERE `ts`>'2014-01-01 00:00:00' AND `ts`<='2014-01-31 23:59:59'
        AND `event_category`='CLIENT PROFILE'
        GROUP BY idClient,city
    ) as CLIPROFILE
    ON CLIPROFILE.city=OTHERS.city and CLIPROFILE.idClient=OTHERS.idClient

我们要做的是在 Mysql 中进行 FULL Outer Join,因此查询的基本架构如下: the one proposed here

我们如何优化查询?我们一直在尝试不同的索引,左右切换,但 8 小时后仍然没有完成运行,

MySQL服务器是一台Percona MySQL 5.5专用机,2cpu,2GB内存,SSD盘,
我们使用 Percona 工具优化了此类服务器的配置,

任何帮助将非常感激,

谢谢

最佳答案

你正在做一个 UNION 导致 DISTINCT 处理。

通常最好将完全连接重写为左连接加上右连接的不匹配行(如果它是正确的 1:n 连接)

OTHERS LEFT JOIN CLIPROFILE
ON CLIPROFILE.city=OTHERS.city and CLIPROFILE.idClient=OTHERS.idClient
union all
OTHERS RIGHT JOIN CLIPROFILE
ON CLIPROFILE.city=OTHERS.city and CLIPROFILE.idClient=OTHERS.idClient
WHERE OTHERS.idClient IS NULL

此外,您可能会在加入临时表之前在临时表中实现派生表的结果,因此计算只完成一次(我不知道 MySQL 的优化器是否足够智能以自动执行此操作)。

此外,将城市/国家作为单独的列进行分组和加入并在外部步骤中将 CONCAT(city,', ',country) 作为城市可能会更有效。

关于mysql - 针对海量数据优化MySQL Full外连接,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/22284887/

10-12 12:46
查看更多