Question

我编写了以下查询，该查询在我的本地服务器上运行大约40秒，但在托管的mysql服务器上继续运行。有人可以帮忙并确定如何改进它吗？

Set @rownum = 0;
Set @rownum1 = 0;
explain select * from 
(select *, @rownum1:=@rownum1+1 as ida from xvp_tenant_683.activity_archive_90) tbl1
where tbl1.ida >
(select id from
(select *, @rownum:=@rownum+1 as id from xvp_tenant_683.activity_archive_90) tbl
where ctype = 'WRAPUP' and dtStart = '2015-10-01 17:08:59' and uid='30774' and 
cprofiletype = 'inbound' and pid = '53');

表结构是：

CREATE TABLE `activity_archive_90` (
  `cType` varchar(20) NOT NULL DEFAULT '',
  `dtStart` datetime NOT NULL DEFAULT '1900-01-01 00:00:00',
  `dtEnd` datetime NOT NULL DEFAULT '1900-01-01 00:00:00',
  `iDuration` int(11) NOT NULL DEFAULT '0',
  `dRevenue` decimal(10,2) NOT NULL DEFAULT '0.00',
  `uId` int(11) NOT NULL DEFAULT '0',
  `cUserName` varchar(100) NOT NULL DEFAULT '',
  `cProfileType` varchar(10) NOT NULL DEFAULT '',
  `pId` int(11) NOT NULL DEFAULT '0',
  `ccId` int(11) NOT NULL DEFAULT '0',
  `ibProfiles` text,
  `obProfiles` text,
  PRIMARY KEY (`cType`,`dtStart`,`uId`,`cProfileType`,`pId`),
  KEY `cType` (`cType`),
  KEY `dtStart` (`dtStart`),
  KEY `dtEnd` (`dtEnd`),
  KEY `uId` (`uId`),
  KEY `pId` (`pId`),
  KEY `ccId` (`ccId`),
  KEY `cProfileType` (`cProfileType`),
  KEY `cUserName` (`cUserName`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

在托管服务器上解释声明结果是：

# id, select_type, table, type, possible_keys, key, key_len, ref, rows, Extra
1, PRIMARY, <derived2>, ALL, , , , , 333708, Using where
3, UNCACHEABLE SUBQUERY, <derived4>, ALL, , , , , 333708, Using where
4, DERIVED, activity_archive_90, ALL, , , , , 333708, 
2, DERIVED, activity_archive_90, ALL, , , , , 333708,

在我的本地服务器上解释语句结果是：

# id, select_type, table, type, possible_keys, key, key_len, ref, rows, Extra
1, PRIMARY, <derived2>, ALL, , , , , 333525, Using where
3, UNCACHEABLE SUBQUERY, <derived4>, ref, <auto_key0>, <auto_key0>, 47, const,const,const,const,const, 10, Using index condition
4, DERIVED, zzz_activity_archive_90, ALL, , , , , 333525, 
2, DERIVED, zzz_activity_archive_90, ALL, , , , , 333525,

我注意到第二个结果使用了一个键，这可能是我本地服务器上更快结果的原因？如何在托管服务器上包含此密钥（我无权访问托管服务器上的alter table）

改进查询：从没有主键的特定点选择mysql表中的数据

0 个答案: