mysql 显示SQL语句执行时间的代码
mysql 的 sql 語法調整主要都是使用 explain , 但是這個並沒辦法知道詳細的 ram(memory)/cpu 等使用量.
於 mysql 5.0.37 以上開始支援 mysql query profiler, 可以查詢到此 sql 會執行多少時間, 並看出 cpu/memory 使用量, 執行過程中 system lock, table lock 花多少時間等等.
mysql query profile 詳細介紹可見: using the new mysql query profiler (2007.04.05 發表)
效能分析主要分下述三種(轉載自上篇):
bottleneck analysis - focuses on answering the questions: what is my database server waiting on; what is a user connection waiting on; what is a piece of sql code waiting on?
workload analysis - examines the server and who is logged on to determine the resource usage and activity of each.
ratio-based analysis - utilizes a number of rule-of-thumb ratios to gauge performance of a database, user connection, or piece of code.
mysql query profile 使用方法
啟動
mysql> set profiling=1; # 此命令於 mysql 會於 information_schema 的 database 建立一個 profiling 的 table 來紀錄.
sql profiles show
mysql> show profiles; # 從啟動之後所有語法及使用時間, 含錯誤語法都會紀錄.
ex: () [test]> show profiles; # 注意 query_id, 下面執行時間統計等, 都是依 query_id 在紀錄
+----------+------------+---------------------------+
| query_id | duration | query |
+----------+------------+---------------------------+
| 1 | 0.00090400 | show profile for query 1 |
| 2 | 0.00008700 | select * from users |
| 3 | 0.00183800 | show tables |
| 4 | 0.00027600 | mysql> show profiles |
+----------+------------+---------------------------+
查詢所有花費時間加總
mysql> select sum(duration) from information_schema.profiling where query_id=1; # query id = 1
+---------------+
| sum(duration) |
+---------------+
| 0.000447 |
+---------------+
查詢各執行階段花費多少時間
mysql> show profile for query 1; # query id = 1
+--------------------+------------+
| status | duration |
+--------------------+------------+
| (initialization) | 0.00006300 |
| opening tables | 0.00001400 |
| system lock | 0.00000600 |
| table lock | 0.00001000 |
| init | 0.00002200 |
| optimizing | 0.00001100 |
| statistics | 0.00009300 |
| preparing | 0.00001700 |
| executing | 0.00000700 |
| sending data | 0.00016800 |
| end | 0.00000700 |
| query end | 0.00000500 |
| freeing items | 0.00001200 |
| closing tables | 0.00000800 |
| logging slow query | 0.00000400 |
+--------------------+------------+
查詢各執行階段花費的各種資源列表
mysql> show profile cpu for query 1; # query id = 1
+--------------------------------+----------+----------+------------+
| status | duration | cpu_user | cpu_system |
+--------------------------------+----------+----------+------------+
| (initialization) | 0.000007 | 0 | 0 |
| checking query cache for query | 0.000071 | 0 | 0 |
| opening tables | 0.000024 | 0 | 0 |
| system lock | 0.000014 | 0 | 0 |
| table lock | 0.000055 | 0.001 | 0 |
| init | 0.000036 | 0 | 0 |
| optimizing | 0.000013 | 0 | 0 |
| statistics | 0.000021 | 0 | 0 |
| preparing | 0.00002 | 0 | 0 |
| executing | 0.00001 | 0 | 0 |
| sending data | 0.015072 | 0.011998 | 0 |
| end | 0.000021 | 0 | 0 |
| query end | 0.000011 | 0 | 0 |
| storing result in query cache | 0.00001 | 0 | 0 |
| freeing items | 0.000018 | 0 | 0 |
| closing tables | 0.000019 | 0 | 0 |
| logging slow query | 0.000009 | 0 | 0 |
+--------------------------------+----------+----------+------------+
mysql> show profile ipc for query 1;
+--------------------------------+----------+---------------+-------------------+
| status | duration | messages_sent | messages_received |
+--------------------------------+----------+---------------+-------------------+
| (initialization) | 0.000007 | 0 | 0 |
| checking query cache for query | 0.000071 | 0 | 0 |
| opening tables | 0.000024 | 0 | 0 |
| system lock | 0.000014 | 0 | 0 |
| table lock | 0.000055 | 0 | 0 |
| init | 0.000036 | 0 | 0 |
| optimizing | 0.000013 | 0 | 0 |
| statistics | 0.000021 | 0 | 0 |
| preparing | 0.00002 | 0 | 0 |
| executing | 0.00001 | 0 | 0 |
| sending data | 0.015072 | 0 | 0 |
| end | 0.000021 | 0 | 0 |
| query end | 0.000011 | 0 | 0 |
| storing result in query cache | 0.00001 | 0 | 0 |
| freeing items | 0.000018 | 0 | 0 |
| closing tables | 0.000019 | 0 | 0 |
| logging slow query | 0.000009 | 0 | 0 |
+--------------------------------+----------+---------------+-------------------+
其它屬性列表
all - displays all information
block io - displays counts for block input and output operations
context switches - displays counts for voluntary and involuntary context switches
ipc - displays counts for messages sent and received
memory - is not currently implemented
page faults - displays counts for major and minor page faults
source - displays the names of functions from the source code, together with the name and line number of the file in which the function occurs
swaps - displays swap counts
設定 profiling 存的 size
mysql> show variables where variable_name='profiling_history_size'; # 預設是 15筆
關閉
mysql> set profiling=0;