set global slow_query_log = on;
set global long_query_time = 1;
show global variables like "datadir";
show global variables like "slow_query_log_file";

# Time: 2023-08-28T08:25:15.955234Z
# User@Host: root[root] @ localhost []  Id:     8
# Query_time: 0.014107  Lock_time: 0.001830 Rows_sent: 10  Rows_examined: 10
use test;
SET timestamp=1693211115;
select * from yue;
             
/*
Time：慢查询发生的时间
User@Host：客户端用户和IP
Query_time：查询时间
Lock_time：等待表锁的时间
Rows_sent：语句返回的行数
Rows_examined：语句执行期间从存储引擎读取的行数
*/

CREATE TABLE `t1`
`id` int(11) NOT NULL auto_increment,
`a` int(11) DEFAULT NULL,
`b` int(11) DEFAULT NULL,
`create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '记录创建时间',
`update_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '记录更新时间',PRIMARY KEY (`id`),
KEY `idx_a` (`a`),
KEY `idx_b` (`b`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;



delimiter ;;
create procedure insert_t1()
begin
declare i int;
set i=1; 
while(i<=1000)
do 
insert into t1(a,b) values(i, i);
set i=i+1; 
end while;
end;;
delimiter ; 
call insert_t1();

create table t2 like t1; 
insert into t2 select * from t1;

root@ 14:44: [test]> explain select * from t1 where b = 100;
+----+-------------+-------+------------+------+---------------+-------+---------+-------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key   | key_len | ref   | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+-------+---------+-------+------+----------+-------+
|  1 | SIMPLE      | t1    | NULL       | ref  | idx_b         | idx_b | 5       | const |    1 |   100.00 | NULL  |
+----+-------------+-------+------------+------+---------------+-------+---------+-------+------+----------+-------+