1

问题：

  1. 查询在 10 分钟后中止
  2. 查询应该更快

我创建了以下查询。这是几个版本中最快的一个。不幸的是，有了更多数据，即使这个数据在 600 秒后也会出现错误“错误代码：2013。在查询期间丢失与 MySQL 服务器的连接”。

    CREATE OR REPLACE VIEW 1 AS
    SELECT `Timeperiod`    AS `Timeperiod`    ,
           "at"            AS `Domain`        ,
           `Content Groups`AS `Content Groups`,
    ...
    FROM   a

UNION ALL

SELECT `Timeperiod`    AS `Timeperiod`    ,
       "com"           AS `Domain`        ,
       `Content Groups`AS `Content Groups`,
       ...
FROM   b

UNION ALL

SELECT `Timeperiod`    AS `Timeperiod`    ,
       "com"                 AS `Domain`,
       `Content Groups`AS `Content Groups`,
       ...
FROM   c

UNION ALL

SELECT `Timeperiod`    AS `Timeperiod`    ,
       "fr"                 AS `Domain`,
       `Content Groups`AS `Content Groups`,
       ...
FROM   d

UNION ALL

SELECT `Timeperiod`    AS `Timeperiod`    ,
       "it"                 AS `Domain`,
       `Content Groups`AS `Content Groups`,
       ...
FROM   e;

CREATE OR REPLACE VIEW 2 AS
SELECT `Timeperiod`        AS `Timeperiod`       ,
       `Content Group`     AS `Content Group`    ,
       "at"                AS `Domain`,
       ...
FROM   f

UNION ALL

SELECT `Timeperiod`        AS `Timeperiod`       ,
       `Content Group`     AS `Content Group`    ,
       "com"               AS `Domain`,
       ...
FROM g

UNION ALL

SELECT `Timeperiod`        AS `Timeperiod`       ,
       `Content Group`     AS `Content Group`    ,
       "com"               AS `Domain`,
       ...
FROM h

UNION ALL

SELECT `Timeperiod`        AS `Timeperiod`       ,
       `Content Group`     AS `Content Group`    ,
       "fr"                AS `Domain`,
       ...
FROM   i

UNION ALL

SELECT `Timeperiod`        AS `Timeperiod`       ,
       `Content Group`     AS `Content Group`    ,
       "it"                AS `Domain`,
       ...    
FROM   j;

CREATE OR REPLACE VIEW 3 AS
SELECT CG.`Domain`                                        AS `Domain`             ,
       TP.`TimeperiodAlias`                               AS `Timeperiod`         ,
       CG.`Content Groups`                                AS `Content Group`      ,
       M.`InternalName`                                   AS `Internal Model Name`,
       ...
FROM   1 CG                      ,
       Timperiods TP             ,
       Models M
WHERE  CG.`Content Groups` LIKE CONCAT(M.`ContentGroupName`, '%')
AND    CG.`Timeperiod`        = TP.`Timeperiod`;

CREATE OR REPLACE VIEW 4 AS
SELECT CGD.`Domain`                                              AS `Domain`        ,
       TP.`TimeperiodAlias`                                      AS `Timeperiod`    ,
       CGD.`Content Group`                                       AS `Content Group`,
       ...
FROM   2 CGD,
       Timeperiods TP                 ,
       Models M 
WHERE  CGD.`Content Group` LIKE CONCAT(M.`ContentGroupName`, '%')
AND    CGD.`Timeperiod`       = TP.`Timeperiod`;

DROP TABLE IF EXISTS 5;

CREATE TABLE IF NOT EXISTS 5
             (
                          `Domain`     VARCHAR(3) NOT NULL ,
                          `Timeperiod` VARCHAR(30) NOT NULL,
                          `Content Group` varchar(70),
                          `Internal Model Name` VARCHAR(50),
                          ...
                           PRIMARY KEY (`Domain`,`Timeperiod`, `Content Group`)
             )    
AS        

SELECT CG.`Domain`              AS `Domain`             ,
       CG.`Timeperiod`          AS `Timeperiod`         ,
       CG.`Content Group`       AS `Content Group`      ,
       CG.`Internal Model Name` AS `Internal Model Name`,
       ...
FROM   3 CG,
       4 CGD
WHERE  CG.`Content Group` = CGD.`Content Group`
AND    CG.`Timeperiod`    = CGD.`Timeperiod`
AND    CG.`Domain`        = CGD.`Domain`;

这些是步骤的行数：

1：64763 2：51932

时间段：36

型号：15

3：2706

4：2172

这是解释：

'1', 'PRIMARY', 'M', 'ALL', NULL, NULL, NULL, NULL, '15', ''
'1', 'PRIMARY', 'M', 'index', NULL, 'CGIndex', '242', NULL, '15', 'Using index; Using join buffer'
'1', 'PRIMARY', '<derived3>', 'ALL', NULL, NULL, NULL, NULL, '9528', 'Using where; Using join buffer'
'1', 'PRIMARY', 'TP', 'eq_ref', 'PRIMARY', 'PRIMARY', '65', 'CG.Timeperiod', '1', ''
'1', 'PRIMARY', '<derived9>', 'ALL', NULL, NULL, NULL, NULL, '21226', 'Using where; Using join buffer'
'1', 'PRIMARY', 'TP', 'eq_ref', 'PRIMARY', 'PRIMARY', '65', 'CGD.Timeperiod', '1', 'Using where'
'9', 'DERIVED', 'ContentGroupDuration_jMKL35_ALL', 'ALL', NULL, NULL, NULL, NULL, '17794', ''
'10', 'UNION', 'ContentGroupDurationVisitDuration_k4cZ5M_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
'11', 'UNION', 'ContentGroupDurationVisitDuration_k4cZ5M_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
'12', 'UNION', 'ContentGroupDuration_jMKL35_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
'13', 'UNION', 'ContentGroupDuration_jMKL35_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
NULL, 'UNION RESULT', '<union9,10,11,12,13>', 'ALL', NULL, NULL, NULL, NULL, NULL, ''
'3', 'DERIVED', 'ContentGroups_fd33ef1_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
'4', 'UNION', 'ContentGroups_fd33ef1_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
'5', 'UNION', 'ContentGroups_fd33ef1_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
'6', 'UNION', 'ContentGroups_fd33ef1_ALL', 'ALL', NULL, NULL, NULL, NULL, '10476', ''
'7', 'UNION', 'ContentGroups_fd33ef1_ALL', 'ALL', NULL, NULL, NULL, NULL, '1', ''
NULL, 'UNION RESULT', '<union3,4,5,6,7>', 'ALL', NULL, NULL, NULL, NULL, NULL, ''

有谁知道如何加快查询和/或如何避免连接中止？

解决方案：

问题1：从命令行执行“set wait_timeout=2147483”（不在sql里面）

问题2：将中间结果存储在临时表中并添加索引。然后执行大连接。

最好的

基督教

4

1 回答 1

0

我想说有两种方法： - 要么更改非交互式连接的超时时间（Mysql 的 wait_timeout） - 要么以某种方式优化你的表结构

我过去一直在研究大型商业数据库，连接的性能更多地与表作为索引的方式有关，而不是与获取的行数有关。确保正确的表具有正确的键，如果可能，尝试增加这些键。

无论如何，更改 wait_timeout，如果您允许长时间和复杂的查询，连接不应该这么快就死掉。

要更改超时，请以 root 身份登录 mysql：mysql -u root -p，输入密码，然后输入以下内容：set global wait_timeout=2147483

这是对应于 Windows 上 23 天的最大值。在 Linux 发行版上它可以变得更高，但无论如何你不需要那么长的时间。

干杯，

于 2011-11-04T15:36:52.810 回答