Question

我有一个名为prog的主表，如下所示：

CREATE TABLE `prog` (
 `prog_id` int(11) NOT NULL AUTO_INCREMENT,
 `prog_insert_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `prog_edit_date` varchar(16) COLLATE utf8_persian_ci DEFAULT NULL,
 `prog_name` text COLLATE utf8_persian_ci NOT NULL,
 `prog_desc` text COLLATE utf8_persian_ci NOT NULL,
 PRIMARY KEY (`prog_id`),
 KEY `prog_insert_date` (`prog_sabt_date`),
 KEY `prog_edit_date` (`prog_edit_date`)
) ENGINE=InnoDB AUTO_INCREMENT=1;

INSERT INTO prog VALUES
(1,'1395-01-01 11:00','1395-01-01 12:00','prog A', 'prog A description'),
(2,'1395-01-02 11:00','1395-01-02 12:00','prog B', 'prog B description'),
(3,'1395-01-03 11:00','1395-01-03 12:00','prog C', 'prog C description');

由于我需要在我的应用程序中使用Jalali日历，因此我决定将varchar（16）用于日期列并以这种格式保存：'1395-07-20 12:43'。

我还有三个相似的表，其中包含与每个prog_id对应的多个行。他们是信贷，基金和薪酬如下：

CREATE TABLE `credit` (
 `credit_id` int(11) NOT NULL AUTO_INCREMENT,
 `credit_insert_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `credit_edit_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `credit_prog` int(11) NOT NULL,
 `credit_amount` bigint(20) NOT NULL,
 `credit_desc` text COLLATE utf8_persian_ci NOT NULL,
 PRIMARY KEY (`credit_id`),
 KEY `credit_prog` (`credit_prog`),
 KEY `credit_insert_date` (`credit_insert_date`),
 KEY `credit_edit_date` (`credit_edit_date`)
) ENGINE=InnoDB AUTO_INCREMENT=1;

INSERT INTO credit VALUES
(1,'1395-02-01 11:00','1395-02-01 12:00',1, 100000, 'sample description'),
(2,'1395-02-02 11:00','1395-02-02 12:00',1, 200000, 'sample description'),
(3,'1395-02-03 11:00','1395-02-03 12:00',2, 300000, 'sample description'),
(4,'1395-02-04 11:00','1395-02-04 12:00',2, 400000, 'sample description'),
(5,'1395-02-05 11:00','1395-02-05 12:00',3, 500000, 'sample description'),
(6,'1395-02-06 11:00','1395-02-06 12:00',3, 600000, 'sample description');

CREATE TABLE `fund` (
 `fund_id` int(11) NOT NULL AUTO_INCREMENT,
 `fund_insert_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `fund_edit_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `fund_prog` int(11) NOT NULL,
 `fund_amount` bigint(20) NOT NULL,
 `fund_desc` text COLLATE utf8_persian_ci NOT NULL,
 PRIMARY KEY (`fund_id`),
 KEY `fund_prog` (`fund_prog`),
 KEY `fund_insert_date` (`fund_insert_date`),
 KEY `fund_edit_date` (`fund_edit_date`)
) ENGINE=InnoDB AUTO_INCREMENT=1;

INSERT INTO fund VALUES
(1,'1395-03-01 11:00','1395-03-01 12:00',1, 10000, 'sample description'),
(2,'1395-03-02 11:00','1395-03-02 12:00',1, 20000, 'sample description'),
(3,'1395-03-03 11:00','1395-03-03 12:00',2, 30000, 'sample description'),
(4,'1395-03-04 11:00','1395-03-04 12:00',2, 40000, 'sample description'),
(5,'1395-03-05 11:00','1395-03-05 12:00',3, 50000, 'sample description'),
(6,'1395-03-06 11:00','1395-03-06 12:00',3, 60000, 'sample description');

CREATE TABLE `pay` (
 `pay_id` int(11) NOT NULL AUTO_INCREMENT,
 `pay_insert_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `pay_edit_date` varchar(16) COLLATE utf8_persian_ci NOT NULL,
 `pay_prog` int(11) NOT NULL,
 `pay_amount` bigint(20) NOT NULL,
 `pay_desc` text COLLATE utf8_persian_ci NOT NULL,
 PRIMARY KEY (`pay_id`),
 KEY `pay_prog` (`pay_prog`),
 KEY `pay_insert_date` (`pay_insert_date`),
 KEY `pay_edit_date` (`pay_edit_date`)
) ENGINE=InnoDB AUTO_INCREMENT=1;

INSERT INTO pay VALUES
(1,'1395-04-01 11:00','1395-04-01 12:00',1, 1000, 'sample description'),
(2,'1395-04-02 11:00','1395-04-02 12:00',1, 2000, 'sample description'),
(3,'1395-04-03 11:00','1395-04-03 12:00',2, 3000, 'sample description'),
(4,'1395-04-04 11:00','1395-04-04 12:00',2, 4000, 'sample description'),
(5,'1395-04-05 11:00','1395-04-05 12:00',3, 5000, 'sample description'),
(6,'1395-04-06 11:00','1395-04-06 12:00',3, 6000, 'sample description');

现在我希望每个编程行都有相应的信用，基金和工资总和，以及应该从所有表格构建的最后编辑日期。我的疑问是：

SELECT
  prog_id,
  GREATEST(IFNULL(credit_edit_date,''),IFNULL(fund_edit_date,''),IFNULL(pay_edit_date,'')) last_edit_date,
  prog_name,
  credit_amount,
  fund_amount,
  pay_amount,
  prog_desc
FROM prog
LEFT JOIN (
   SELECT
        credit_prog,
        sum(credit_amount) as credit_amount,
        max(credit_edit_date) as credit_edit_date
    FROM credit GROUP BY credit_prog
) as credit ON credit_prog=prog_id
LEFT JOIN (
   SELECT 
        fund_prog,
        sum(fund_amount) as fund_amount,
        max(fund_edit_date) as fund_edit_date
    FROM fund GROUP BY fund_prog
) as fund ON fund_prog=prog_id
LEFT JOIN (
   SELECT 
        pay_prog,
        sum(pay_amount) as pay_amount,
        max(pay_edit_date) as pay_edit_date
    FROM pay GROUP BY pay_prog
) as pay ON pay_prog=prog_id
ORDER BY (SELECT last_edit_date) DESC

我得到了真实的结果，但是在表中有几行的实际情况下，响应需要很长时间。我认为主要问题是last_edit_date列，因为MYSQL优化器不能考虑子查询中这些日期字段的索引。

sqlfiddle

是否有提高执行时间的想法？

Answer 1

如果您的subquerys正在使用除主键之外的索引（并且它们可能会这样做），这实际上会减慢您的查询速度，因为它会使MySQL跳回并强制进入表中而不是将整个表读入内存并在那里做其余的事。

尝试添加以下索引：

alter table credit add index 
  idx_credit_p_a_ed(credit_prog, credit_amount, credit_edit_date);
alter table pay add index 
  idx_pay_p_a_ed(pay_prog, pay_amount, pay_edit_date);
alter table fund add index 
  idx_fund_p_a_ed(fund_prog, fund_amount, fund_edit_date);

如果您不使用MySQL 5.7（或者由于某些其他原因它没有使用这些索引），您可能必须强制它使用它们，所以添加例如。

... FROM credit force index (idx_credit_p_a_ed) GROUP BY credit_prog ...

到子查询。

如果将日期列更改为每字符1个字节的数据类型，例如，可以获得一些额外的速度。使用latin1_swedish_ci代替utf8_persian_ci，因为您只是在那里存储日期。这将减少您的索引和表格大小，从而降低速度（可能显着）。

另外，将ORDER BY (SELECT last_edit_date) DESC更改为ORDER BY last_edit_date DESC。

如何提高我的mysql查询执行性能

1 个答案: