如何加快查询执行MySQL

Question

您必须填写表1至表1,000,000：

Table view
CREATE TABLE `test` ( `id` INT UNSIGNED NOT NULL AUTO_INCREMENT , `value` INT UNSIGNED NOT NULL , PRIMARY KEY (`id`)) ENGINE = InnoDB;"

我编写了一个函数来完成这个任务，但是将数据添加到表中太慢了，如何提高insert数据的性能？

function InsertData(){

    global $MySQL;
    for($i = 1; $i != 1000000; $i++){
        $MySQL->query("INSERT INTO `name` (`id`, `value`) VALUES ($i, $i);");
    }

    $MySQL->close();
}

Answer 1

您可以使用事务，以便每千次插入只提交一次(或者，如果您勇敢的话，在百万次查询之后)。下面是(勇敢的)例子：

function InsertData(){
   global $MySQL;

   // Start transactions
   $MySQL->query('SET autocommit=0;');
   $MySQL->query('START TRANSACTION;');

   for($i = 1; $i != 1000000; $i++){
      $MySQL->query("INSERT INTO `name` (`id`, `value`) VALUES ($i, $i);");
   }
   // So far, nothing as actually been saved to database
  
   // Commit all inserts.
   $MySQL->query('COMMIT;');
   $MySQL->query('SET autocommit=1;');

   $MySQL->close();
}

如果由于某些MySQL限制，这对于单个事务来说太大了，那么您可以每10.000次插入一次提交：

function InsertData(){
   global $MySQL;

   // Start transactions
   $MySQL->query('SET autocommit=0;');
   $MySQL->query('START TRANSACTION;');

   for($i = 1; $i != 1000000; $i++){
      $MySQL->query("INSERT INTO `name` (`id`, `value`) VALUES ($i, $i);");
      if($i % 10000 == 0) {
         $MySQL->query('COMMIT;');
         $MySQL->query('START TRANSACTION;');
      }
   }
   // So far, nothing as actually been saved to database
  
   // Commit all inserts.
   $MySQL->query('COMMIT;');
   $MySQL->query('SET autocommit=1;');

   $MySQL->close();
}

注意-> https://stackoverflow.com/a/2298325/2814721的最终极限

当然，这是一个实验或者一次拍摄的剧本。不建议在生产数据库中这样做。

Answer 2

如何使用递归CTE将逻辑移动到数据库？

insert into name (id, value)
with recursive cte as (
    select 1 id
    union all select id + 1 from cte where i < 1000000
)
select id, id from cte

这可能是要用递归同时生成的行数。另一种方法是只生成10行，然后乘以这些行：

insert into name (id, value)
with recursive cte as (
    select 0 id
    union all select id + 1 from cte where i < 9
)
select id, id 
from (
    select 1 + c0.id + c1.id * 10 + c2.id * 100 + c3.id * 1000 + c4.id * 10000 + c5.id * 100000 id
    cte c0
    cross join cte c1
    cross join cte c2
    cross join cte c3
    cross join cte c4
    cross join cte c5
) t

Answer 3

请尝试以下查询：

INSERT INTO `test` (`id`, `value`) 
SELECT @row := @row + 1 AS row, @row 
FROM (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS t1,
     (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS t2, 
     (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS t3, 
     (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS t4, 
     (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS t5, 
     (SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) AS t6, 
     (SELECT @row:=0) AS nums;

是“插入.选择.”语句类型，其中SELECT语句本身生成百万行，其中填充对(1,1)，(2,2)等。下面是它的工作方式：

1. 表t1、t2、t3、t4、t5、t6各为10行。交叉连接它们将生成10^6 = 1000000的组合，因此生成的表将包含百万行；对于其中的每一行，我们将选择两次@row变量。不仅如此，我们还用1来增加它；

，

1. ，nums表在开始时只用于将变量初始化为0；
2. ，结果表被传递给INSERT语句，数据存储在表中。

一个更清晰的解决方案是在更新的MySQL/MariaDB中使用递归CTE。是the one that was submitted by user GMB

INSERT INTO test (id, value)
WITH RECURSIVE temp AS (
    SELECT 1 AS row
    UNION SELECT row + 1 
    FROM temp
    WHERE row < 1000000
)
SELECT row, row
FROM temp;

根据我的测试，速度有点慢。我没有监控内存的使用情况。