|
2'),
('July', 23, 'dev5', '2018-06-04 16:02:02'),
('July', 23, 'dev7', '2018-06-04 16:02:02'),
('July', 23, 'dev8', '2018-06-04 16:02:02'),
('July', 23, 'dev9', '2018-06-04 16:02:02'),
('July', 23, 'dev10', '2018-06-04 16:02:02'),
('Clive', 23, 'dev1', '2018-06-04 16:02:02'),
('Clive', 23, 'dev2', '2018-06-04 16:02:02'),
('Clive', 23, 'dev3', '2018-06-04 16:02:02'),
('Clive', 23, 'dev4', '2018-06-04 16:02:02'),
('Clive', 23, 'dev6', '2018-06-04 16:02:02'),
('Clive', 23, 'dev5', '2018-06-04 16:02:02'),
('Clive', 23, 'dev7', '2018-06-04 16:02:02'),
('Clive', 23, 'dev8', '2018-06-04 16:02:02'),
('Clive', 23, 'dev9', '2018-06-04 16:02:02'),
('Clive', 23, 'dev10', '2018-06-04 16:02:02');
执行Explain
-- 再次执行同样的查询语句，会发现走到索引上了
explain select * from staffs where name = 'July' and age = 23;
id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1 SIMPLE staffs NULL ref idx_nap idx_nap 78 const,const 13 100.00 NULL
查看新的Trace内容
-- 再看下优化器执行过程
{
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `staffs`.`id` AS `id`,`staffs`.`name` AS `name`,`staffs`.`age` AS `age`,`staffs`.`pos` AS `pos`,`staffs`.`add_time` AS `add_time` from `staffs` where ((`staffs`.`name` = 'July') and (`staffs`.`age` = 23))"
}
]
}
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`staffs`.`name` = 'July') and (`staffs`.`age` = 23))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "((`staffs`.`name` = 'July') and multiple equal(23, `staffs`.`age`))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "((`staffs`.`name` = 'July') and multiple equal(23, `staffs`.`age`))"
},
|