MySQL/MariaDB的"response time"插件

“响应时间”是衡量数据库性能的常用指标。在MariaDB中可以使用插件“QUERY_RESPONSE_TIME”来获取查询时间区间的统计信息。

// 安装插 件

$ cd ${mysql_base}/lib/plugin
$ ll
-rw-r--r--. 1 root root 403898 Feb 25 01:15 query_response_time.so

MariaDB [(none)]> install plugin query_response_time_audit soname 'query_response_time.so';
MariaDB [(none)]> install plugin query_response_time soname 'query_response_time.so';
MariaDB [(none)]> show plugins;
...
| QUERY_RESPONSE_TIME_AUDIT     | ACTIVE   | AUDIT              | query_response_time.so | GPL     |
| QUERY_RESPONSE_TIME           | ACTIVE   | INFORMATION SCHEMA | query_response_time.so | GPL     |
+-------------------------------+----------+--------------------+------------------------+---------+

// 参数说明

MariaDB [(none)]> show variables like 'query_response%';
+--------------------------------+-------+
| Variable_name                  | Value |
+--------------------------------+-------+
| query_response_time_flush      | OFF   |    
| query_response_time_range_base | 10    |	 
| query_response_time_stats      | OFF   |
+--------------------------------+-------+
3 rows in set (0.00 sec)

query_response_time_flush

Description: Updating this variable flushes the statistics and re-reads query_response_time_range_base.
Commandline: None
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: OFF

query_response_time_range_base
Description: Select base of log for QUERY_RESPONSE_TIME ranges. WARNING: variable change takes affect only after flush.
Commandline: --query-response-time-range-base=#
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 10
Range: 2 to 1000

if the range base=10, we have the following intervals:
(0; 10 ^ -6], (10 ^ -6; 10 ^ -5], (10 ^ -5; 10 ^ -4], ..., 
  (10 ^ -1; 10 ^1], (10^1; 10^2]...(10^7; positive infinity]

query_response_time_stats
Description: Enable or disable query response time statistics collecting
Commandline: query-response-time-stats[={0|1}]
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: OFF

// 打开统计

MariaDB [(none)]> set global query_response_time_stats = 1;
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> set global query_response_time_flush='ON';
Query OK, 0 rows affected (0.00 sec)

MariaDB [information_schema]> select * from information_schema.QUERY_RESPONSE_TIME;
+----------------+-------+----------------+
| TIME           | COUNT | TOTAL          |
+----------------+-------+----------------+
|       0.000001 |     0 |       0.000000 |
|       0.000010 |     0 |       0.000000 |
|       0.000100 |    70 |       0.002200 |
|       0.001000 |    16 |       0.005615 |
|       0.010000 |     0 |       0.000000 |
|       0.100000 |     0 |       0.000000 |
|       1.000000 |     0 |       0.000000 |
|      10.000000 |     0 |       0.000000 |
|     100.000000 |     0 |       0.000000 |
|    1000.000000 |     0 |       0.000000 |
|   10000.000000 |     0 |       0.000000 |
|  100000.000000 |     0 |       0.000000 |
| 1000000.000000 |     0 |       0.000000 |
| TOO LONG       |     0 | TOO LONG       |
+----------------+-------+----------------+
14 rows in set (0.00 sec)

// 分析
从上面的记录可知：
有70个查询的执行时间在0.000010秒<query execution time < =0.000100秒这个区间里；耗时总计0.002200秒。
有16个查询的执行时间在0.000100秒<query execution time < =0.001000秒这个区间里；耗时总计0.005615秒。