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MYSQL必讀1, see the slow log status;

MYSQL必讀mysql> show variables like '%slow%';
+---------------------+------------------------------------------+
| Variable_name?????? | Value??????????????????????????????????? |
+---------------------+------------------------------------------+
| log_slow_queries??? | ON?????????????????????????????????????? |
| slow_launch_time??? | 2??????????????????????????????????????? |
| slow_query_log????? | ON?????????????????????????????????????? |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306.log |
+---------------------+------------------------------------------+
4 rows in set (0.00 sec)

MYSQL必讀2, stop the slow log server.

MYSQL必讀mysql> set global slow_query_log=0;
Query OK, 0 rows affected (0.27 sec)

MYSQL必讀mysql> show variables like '%slow%';
+---------------------+------------------------------------------+
| Variable_name?????? | Value??????????????????????????????????? |
+---------------------+------------------------------------------+
| log_slow_queries??? | OFF????????????????????????????????????? |
| slow_launch_time??? | 2??????????????????????????????????????? |
| slow_query_log????? | OFF????????????????????????????????????? |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306.log |
+---------------------+------------------------------------------+
4 rows in set (0.00 sec)

MYSQL必讀mysql>
mysql> show variables like '%slow%'; -- check slow log status
+---------------------+------------------------------------------+
| Variable_name?????? | Value??????????????????????????????????? |
+---------------------+------------------------------------------+
| log_slow_queries??? | OFF????????????????????????????????????? |
| slow_launch_time??? | 2??????????????????????????????????????? |
| slow_query_log????? | OFF????????????????????????????????????? |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306.log |
+---------------------+------------------------------------------+
4 rows in set (0.00 sec)

MYSQL必讀3, reset the new path of slow log

MYSQL必讀mysql> set global slow_query_log_file='/mysqllog/slow_log/slow_queries_3306_new.log';
Query OK, 0 rows affected (0.03 sec)

MYSQL必讀4, start the slow log server

MYSQL必讀mysql>
mysql>
mysql> set global slow_query_log=1;
Query OK, 0 rows affected (0.01 sec)

MYSQL必讀
mysql> show variables like '%slow%';
+---------------------+----------------------------------------------+
| Variable_name?????? | Value??????????????????????????????????????? |
+---------------------+----------------------------------------------+
| log_slow_queries??? | ON?????????????????????????????????????????? |
| slow_launch_time??? | 2??????????????????????????????????????????? |
| slow_query_log????? | ON?????????????????????????????????????????? |
| slow_query_log_file | /mysqllog/slow_log/slow_queries_3306_new.log |
+---------------------+----------------------------------------------+
4 rows in set (0.00 sec)

MYSQL必讀5, check the slow sql in the new slow log file.

MYSQL必讀mysql> select sleep(10) as a, 1 as b;
+---+---+
| a | b |
+---+---+
| 0 | 1 |
+---+---+
1 row in set (10.00 sec)

MYSQL必讀mysql>
[mysql@xxx-xxx ~]$ more /mysqllog/slow_log/slow_queries_3306_new.log
......
Time???????????????? Id Command??? Argument
# Time: 140213? 6:44:24
# User@Host: root[root] @ localhost []
# Query_time: 10.000365? Lock_time: 0.000000 Rows_sent: 1? Rows_examined: 0
SET timestamp=1392273864;
select sleep(10) as a, 1 as b;

MYSQL必讀6, backup the old big slow log file to other directory.

MYSQL必讀mv /mysqllog/slow_log/slow_queries_3306.log /mysqlbackup/slow_log/slow_queries_3306.log.bak.20140213

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