1、修改my.cnf或my.ini
1)、linux-----------------------------------
/etc/my.cnf 文件
[mysqld]
long_query_time = 1
log-slow-queries XXXXXXXXX
2)、window--------------------------------
my.ini 文件
[mysqld]
long_query_time = 1log-slow-queries=C:\mysql_slow.log;log-queries-not-using-indexes
2、service mysql restart
3、
方法二：用 mysql 客户端命令行修改，但重启之后会失效
mysql> show variables like 'lo%';+---------------------------------+---------------------+| Variable_name | Value |+---------------------------------+---------------------+| local_infile | ON || lock_wait_timeout | 31536000 || locked_in_memory | OFF || log | OFF || log_bin | ON || log_bin_trust_function_creators | OFF || log_error | /disk/mysql/ || log_output | FILE || log_queries_not_using_indexes | OFF || log_slave_updates | OFF || log_slow_queries | OFF || log_warnings | 1 || long_query_time | 10.000000 || low_priority_updates | OFF || lower_case_file_system | OFF || lower_case_table_names | 0 |+---------------------------------+---------------------+16 rows in set (0.00 sec)mysql> set global long_query_time = 1;Query OK, 0 rows affected (0.00 sec)mysql> set global log_slow_queries = on;Query OK, 0 rows affected, 1 warning (0.31 sec)mysql> set global log_queries_not_using_indexes = on;Query OK, 0 rows affected (0.00 sec)mysql> show variables like 'lo%'; +---------------------------------+---------------------+| Variable_name | Value |+---------------------------------+---------------------+| local_infile | ON || lock_wait_timeout | 31536000 || locked_in_memory | OFF || log | OFF || log_bin | ON || log_bin_trust_function_creators | OFF || log_error | /disk/mysql/ || log_output | FILE || log_queries_not_using_indexes | ON || log_slave_updates | OFF || log_slow_queries | ON || log_warnings | 1 || long_query_time | 10.000000 || low_priority_updates | OFF || lower_case_file_system | OFF || lower_case_table_names | 0 |+---------------------------------+---------------------+16 rows in set (0.00 sec)此处发现一个很奇怪的问题，long_query_time的更改似乎没有生效。过了几分钟，再看，发现已经改过来了。mysql> show variables like 'lo%';+---------------------------------+---------------------+| Variable_name | Value |+---------------------------------+---------------------+| local_infile | ON || lock_wait_timeout | 31536000 || locked_in_memory | OFF || log | OFF || log_bin | ON || log_bin_trust_function_creators | OFF || log_error | /disk/mysql/ || log_output | FILE || log_queries_not_using_indexes | ON || log_slave_updates | OFF || log_slow_queries | ON || log_warnings | 1 || long_query_time | 1.000000 || low_priority_updates | OFF || lower_case_file_system | OFF || lower_case_table_names | 0 |+---------------------------------+---------------------+16 rows in set (0.00 sec)