MySql：优化查询

Question

尝试优化以下查询，因为它运行速度非常慢。我对它做了一些优化但是窗台运行非常慢＆gt; 30秒。

这是查询：

set @_YEAR = 2014;
set @_MONTH = 1;
set @_PRODUCTS = '53';

set @_START = date(@_YEAR * 10000 + 1 * 100 + 1);  
set @_END = date_add(date(@_YEAR * 10000 + 1 * 100 + 1), interval 1 year);

explain SELECT TG, TS, `MONTH` 

FROM (

    SELECT SG.company, SUM(SG.Gain) as TG, SUM(SG.Spill) as TS, SG.`MONTH`

    FROM (

        (SELECT c.called as customer, c.calling as company, MONTH(c.`end`) as 'MONTH',
                @G := if(@prevComp <> c.calling AND @prevCust = c.called AND @prevDate = DATE_FORMAT(c.`end`,'%Y-%m-%d'), 1, 0) as Gain,
                @S := 0 as Spill,
                @prevCust := c.called as prevCust,
                @prevComp := c.calling as prevComp,
                @prevDate := DATE_FORMAT(c.`end`,'%Y-%m-%d') as prevDate
        FROM cdrdata_archive c CROSS JOIN
             (SELECT @prevComp := 0, @prevCust := 0, @prevDate := 0) prevVals
        where c.`end` >= @_START and c.`end` < @_END
        AND c.called != 'Anonymous' 
        AND CAST(c.`duration` AS UNSIGNED) > 30
        ORDER BY c.called, c.`end` limit 5000000)

    UNION ALL

        (SELECT c.called as customer, c.calling as company, MONTH(c.`end`) as 'MONTH',
                @G := 0 as Gain,
                @S := if(@nextComp <> c.calling AND @nextCust = c.called AND @nextDate = DATE_FORMAT(c.`end`,'%Y-%m-%d'), 1, 0) as Spill,
                @nextCust := c.called as nextCust,
                @nextComp := c.calling as nextComp,
                @nextDate := DATE_FORMAT(c.`end`,'%Y-%m-%d') as nextDate
        FROM cdrdata_archive c CROSS JOIN
             (SELECT @nextComp := 0, @nextCust := 0, @nextDate := 0) nextVals
        where c.`end` >= @_START and c.`end` < @_END
        AND c.called != 'Anonymous'
        AND CAST(c.`duration` AS UNSIGNED) > 30
        ORDER BY c.called, c.`end` desc limit 5000000)
    ) SG

     GROUP BY SG.company, SG.`MONTH`

) SGgrouped

JOIN products p ON p.Number = SGgrouped.company
Where p.id IN (@_PRODUCTS)
ORDER BY SGgrouped.`MONTH`

这是输入：

CREATE TABLE `cdrdata_archive` (
  `CustomerID` varchar(10) DEFAULT NULL,
  `callid` varchar(20) NOT NULL,
  `called` varchar(14) DEFAULT NULL,
  `description` varchar(20) DEFAULT NULL,
  `calling` varchar(16) DEFAULT NULL,
  `dtn` varchar(14) DEFAULT NULL,
  `start` datetime DEFAULT NULL,
  `end` datetime DEFAULT NULL,
  `answered` datetime DEFAULT NULL,
  `duration` varchar(5) DEFAULT NULL,
  `talktime` varchar(5) DEFAULT NULL,
  `tta` int(3) DEFAULT NULL,
  PRIMARY KEY (`callid`),
  UNIQUE KEY `callid_UNIQUE` (`callid`),
  KEY `called` (`called`,`start`,`end`),
  KEY `abandoned_from` (`calling`,`talktime`,`end`),
  KEY `called end` (`calling`,`end`),
  KEY `start` (`start`),
  KEY `calling` (`calling`),
  KEY `endcalling` (`end`,`calling`),
  KEY `productdur` (`calling`,`end`,`duration`),
  KEY `endcallingdur` (`end`,`calling`,`duration`),
  KEY `company` (`CustomerID`,`end`),
  KEY `calling end` (`end`,`called`,`calling`),
  KEY `end` (`end`) USING BTREE,
  KEY `call_id_desc` (`callid`) USING BTREE
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

这是EXPLAIN声明：

以下是SHOW VARIABLES LIKE '%buffer%';

的输出

问：如何优化此查询？

Answer 1

主要问题是（参见上面的评论）是你的表格，就像这种类型的CASTING

 AND CAST(c.`duration` AS UNSIGNED) > 30

MySQL不能使用任何KEY，必须扫描整个表。

修改

请出示详细说明

EXPLAIN 
       SELECT c.called as customer, c.calling as company, MONTH(c.`end`) as 'MONTH',
                @G := 0 as Gain,
                @S := if(@nextComp <> c.calling AND @nextCust = c.called AND @nextDate = DATE_FORMAT(c.`end`,'%Y-%m-%d'), 1, 0) as Spill,
                @nextCust := c.called as nextCust,
                @nextComp := c.calling as nextComp,
                @nextDate := DATE_FORMAT(c.`end`,'%Y-%m-%d') as nextDate
        FROM cdrdata_archive c CROSS JOIN
             (SELECT @nextComp := 0, @nextCust := 0, @nextDate := 0) nextVals
        where c.`end` >= @_START and c.`end` < @_END
        AND c.called != 'Anonymous'
        AND CAST(c.`duration` AS UNSIGNED) > 30
        ORDER BY c.called, c.`end` desc 
    limit 5000000

Answer 2

我在另一个论坛上给了你更长的答案。在这个论坛中，我看到一个只有8MB的微不足道的key_buffer_size。建议您将其设置为可用 RAM的约20％。