MySQL.slow_log表里記錄的start_time是語句的什么時間？ 

答：語句的結(jié)束時間 

mysql> select now(); select count(distinct url) from test order by url asc ,example desc ; 
+---------------------+ 
| now() | 
+---------------------+ 
| 2016-01-18 16:25:19 | 
+---------------------+ 
1 row in set (0.00 sec) 

+---------------------+ 
| count(distinct url) | 
+---------------------+ 
| 199 | 
+---------------------+ 
1 row in set (16.15 sec) 



mysql> select *from mysql.slow_log order by start_time desc limit 10\G 
*************************** 1. row *************************** 
start_time: 2016-01-18 16:25:35 
user_host: root[root] @ localhost [] 
query_time: 00:00:16 
lock_time: 00:00:00 
rows_sent: 1 
rows_examined: 824832 
db: test 
last_insert_id: 0 
insert_id: 0 
server_id: 168039296 
sql_text: select count(distinct url) from test order by url asc ,example desc 
thread_id: 4 
1 row in set (0.00 sec) 

start_time為16：25：35 減去query_time: 00:00:16 等于 16:25:19 

所以start_time 記錄的是語句的結(jié)束時間 


slow_log文件里記錄的內(nèi)容是 
# Time: 160118 16:25:35 
# User@Host: root[root] @ localhost [] Id: 4 
# Query_time: 16.152763 Lock_time: 0.000102 Rows_sent: 1 Rows_examined: 824832 
SET timestamp=1453105535; 
select count(distinct url) from test order by url asc ,example desc; 
time和timestamp 值是一樣的， 都是語句的結(jié)束時間