Mysql选错索引分析

create TABLE `test_table2`(
	`id` int(20) NOT NULL AUTO_INCREMENT COMMENT '自增主键',
	`a` int(11) NOT NULL COMMENT '测试字段a',
	`b` int(11) NOT NULL COMMENT '测试字段b' ,
	primary key (`id`),
	key `a` (`a`),
	key `b` (`b`)
	)ENGINE=InnoDB DEFAULT CHARSET=utf8m64 COMMIT='测试表';

set global long_query_time = 0;
set global slow_query_log='ON';
set global slow_query_log_file='/data/instance-1-slow.log';
//验证
select sleep(2);

delimiter ;;
create procedure idata1()
begin 
	declare i int; 
	set i=1; 
	while(i<=100000)do 
		insert into `test_table2`(`a`,`b`) values(i, i); 
		set i=i+1; 
		end while;
	end;;
	delimiter ;
	call idata1();

select @@global.tx_isolation,@@tx_isolation,version(),"session A";

start TRANSACTION with consistent snapshot;

select @@global.tx_isolation,@@tx_isolation,version(),"session B";

delete from `test_table2`;

call idata1();

explain select * from `test_table2` where a between 10000 and 20000;
//Q1
select * from `test_table2` where a between 10000 and 20000;
//Q2
select * from `test_table2` force index(a) where a between 10000 and 20000;

commit;