手冊上介紹：(SHOW PROFILES and SHOW PROFILE were added in MySQL 5.0.37. )
Important
Please note that the SHOW PROFILE and SHOW PROFILES functionality is part of the MySQL 5.0 Community Server only.
2、變量profiling是用戶變量，每次都得重新啟用。
以下是我做的一些實驗。數據很明顯，就不多解釋了。
MySQL> use test
Database changed
MySQL> set profiling=1;
Query OK, 0 rows affected (0.00 sec)
MySQL> show tables;
+----------------+
| Tables_in_test |
+----------------+
| bag_item |
| bag_user |
| score |
| t |
+----------------+
4 rows in set (0.03 sec)
MySQL> select count(*) from t;
+----------+
| count(*) |
+----------+
| 2097152 |
+----------+
1 row in set (0.74 sec)
MySQL> show profiles;
+----------+------------+------------------------+
| Query_ID | Duration | Query |
+----------+------------+------------------------+
| 1 | 0.02717000 | show tables |
| 2 | 0.74770100 | select count(*) from t |
+----------+------------+------------------------+
2 rows in set (0.00 sec)
MySQL> show profile for query 2;
+--------------------------------+----------+
| Status | Duration |
+--------------------------------+----------+
| (initialization) | 0.000004 |
| checking query cache for query | 0.000044 |
| Opening tables | 0.000012 |
| System lock | 0.000017 |
| Table lock | 0.00003 |
| init | 0.000013 |
| optimizing | 0.000008 |
| statistics | 0.000013 |
| preparing | 0.000011 |
| executing | 0.000006 |
| Sending data | 0.747313 |
| end | 0.000014 |
| query end | 0.000006 |
| storing result in query cache | 0.000006 |
| freeing items | 0.000012 |
| closing tables | 0.000009 |
| logging slow query | 0.000183 |
+--------------------------------+----------+
17 rows in set (0.00 sec)
MySQL> show profile block io,cpu for query 2;
+--------------------------------+----------+----------+------------+--------------+---------------+
| Status | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |
+--------------------------------+----------+----------+------------+--------------+---------------+
| (initialization) | 0.000004 | 0 | 0 | 0 | 0 |
| checking query cache for query | 0.000044 | 0 | 0 | 0 | 0 |
| Opening tables | 0.000012 | 0 | 0 | 0 | 0 |
| System lock | 0.000017 | 0 | 0 | 0 | 0 |
| Table lock | 0.00003 | 0 | 0 | 0 | 0 |
| init | 0.000013 | 0 | 0 | 0 | 0 |
| optimizing | 0.000008 | 0 | 0 | 0 | 0 |
| statistics | 0.000013 | 0 | 0 | 0 | 0 |
| preparing | 0.000011 | 0 | 0 | 0 | 0 |
| executing | 0.000006 | 0 | 0 | 0 | 0 |
| Sending data | 0.747313 | 0.746887 | 0 | 0 | 0 |
| end | 0.000014 | 0 | 0 | 0 | 0 |
| query end | 0.000006 | 0 | 0 | 0 | 0 |
| storing result in query cache | 0.000006 | 0 | 0 | 0 | 0 |
| freeing items | 0.000012 | 0 | 0 | 0 | 0 |
| closing tables | 0.000009 | 0 | 0 | 0 | 0 |
| logging slow query | 0.000183 | 0 | 0 | 0 | 0 |
+--------------------------------+----------+----------+------------+--------------+---------------+
17 rows in set (0.00 sec)
MySQL> insert into t(username) select username from t;
Query OK, 2097152 rows affected (34.17 sec)
Records: 2097152 Duplicates: 0 Warnings: 0
MySQL> show profiles;
+----------+-------------+------------------------------------------------+
| Query_ID | Duration | Query |
+----------+-------------+------------------------------------------------+
| 1 | 0.02717000 | show tables |
| 2 | 0.74770100 | select count(*) from t |
| 3 | 0.00004200 | show prifile for query 2 |
| 4 | 34.30410100 | insert into t(username) select username from t |
+----------+-------------+------------------------------------------------+
4 rows in set (0.00 sec)
MySQL> show profile cpu,block io,memory,swaps for query 4;
+------------------------------+-----------+-----------+------------+--------------+---------------+-------+
| Status | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out | Swaps |
+------------------------------+-----------+-----------+------------+--------------+---------------+-------+
| (initialization) | 0.000038 | 0 | 0 | 0 | 0 | 0 |
| checking permissions | 0.000016 | 0 | 0 | 0 | 0 | 0 |
| Opening tables | 0.000014 | 0 | 0 | 0 | 0 | 0 |
| System lock | 0.000007 | 0 | 0 | 0 | 0 | 0 |
| Table lock | 0.000013 | 0 | 0 | 0 | 0 | 0 |
| init | 0.000015 | 0 | 0 | 0 | 0 | 0 |
| optimizing | 0.000006 | 0 | 0 | 0 | 0 | 0 |
| statistics | 0.000012 | 0 | 0 | 0 | 0 | 0 |
| preparing | 0.000011 | 0 | 0 | 0 | 0 | 0 |
| Creating tmp table | 0.000029 | 0 | 0 | 0 | 0 | 0 |
| executing | 0.000005 | 0 | 0 | 0 | 0 | 0 |
| Copying to tmp table | 1.262877 | 1.24981 | 0.012998 | 0 | 0 | 0 |
| converting HEAP to MyISAM | 0.384814 | 0.187971 | 0.19797 | 0 | 0 | 0 |
| Copying to tmp table on disk | 1.417069 | 1.203817 | 0.191971 | 0 | 0 | 0 |
| Sending data | 31.104185 | 13.965877 | 0.843872 | 0 | 0 | 0 |
| end | 0.000017 | 0 | 0 | 0 | 0 | 0 |
| removing tmp table | 0.134872 | 0 | 0.029995 | 0 | 0 | 0 |
| end | 0.000026 | 0 | 0 | 0 | 0 | 0 |
| query end | 0.000006 | 0 | 0 | 0 | 0 | 0 |
| freeing items | 0.000011 | 0 | 0 | 0 | 0 | 0 |
| closing tables | 0.000009 | 0 | 0 | 0 | 0 | 0 |
| logging slow query | 0.000049 | 0 | 0 | 0 | 0 | 0 |
+------------------------------+-----------+-----------+------------+--------------+---------------+-------+
22 rows in set (0.00 sec)
MySQL> select count(*) from t;
+----------+
| count(*) |
+----------+
| 4194304 |
+----------+
1 row in set (1.51 sec)
MySQL> show profiles;
+----------+-------------+------------------------------------------------+
| Query_ID | Duration | Query |
+----------+-------------+------------------------------------------------+
| 1 | 0.02717000 | show tables |
| 2 | 0.74770100 | select count(*) from t |
| 3 | 0.00004200 | show prifile for query 2 |
| 4 | 34.30410100 | insert into t(username) select username from t |
| 5 | 1.50563800 | select count(*) from t |
+----------+-------------+------------------------------------------------+
5 rows in set (0.00 sec)
MySQL> show profile cpu,block io,memory,swaps,context switches,source for query 5;
+--------------------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+-------+---------------------------+---------------+-------------+
| Status | Duration | CPU_user | CPU_system | Context_voluntary | Context_involuntary | Block_ops_in | Block_ops_out | Swaps | Source_function | Source_file | Source_line |
+--------------------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+-------+---------------------------+---------------+-------------+
| (initialization) | 0.000004 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | send_result_to_clIEnt | sql_cache.cc | 1099 |
| checking query cache for query | 0.000048 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | open_tables | sql_base.cc | 2629 |
| Opening tables | 0.000011 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_lock_tables | lock.cc | 153 |
| System lock | 0.000007 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_lock_tables | lock.cc | 162 |
| Table lock | 0.000032 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_select | sql_select.cc | 2242 |
| init | 0.000013 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | optimize | sql_select.cc | 745 |
| optimizing | 0.000008 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | optimize | sql_select.cc | 904 |
| statistics | 0.000013 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | optimize | sql_select.cc | 914 |
| preparing | 0.000011 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | exec | sql_select.cc | 1565 |
| executing | 0.000006 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | exec | sql_select.cc | 2083 |
| Sending data | 1.505401 | 1.504771 | 0 | 3 | 5 | 0 | 0 | 0 | MySQL_select | sql_select.cc | 2287 |
| end | 0.000015 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_execute_command | sql_parse.cc | 5122 |
| query end | 0.000005 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | query_cache_end_of_result | sql_cache.cc | 729 |
| storing result in query cache | 0.000007 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_parse | sql_parse.cc | 6116 |
| freeing items | 0.00001 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | dispatch_command | sql_parse.cc | 2146 |
| closing tables | 0.000009 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | log_slow_statement | sql_parse.cc | 2204 |
| logging slow query | 0.000038 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | dispatch_command | sql_parse.cc | 2169 |
+--------------------------------+----------+----------+------------+-------------------+---------------------+--------------+---------------+-------+---------------------------+---------------+-------------+
17 rows in set (0.00 sec)
MySQL> update t set username = 'waill';
Query OK, 4194304 rows affected (44.82 sec)
Rows matched: 4194304 Changed: 4194304 Warnings: 0
MySQL> show profiles;
+----------+-------------+------------------------------------------------+
| Query_ID | Duration | Query |
+----------+-------------+------------------------------------------------+
| 1 | 0.02717000 | show tables |
| 2 | 0.74770100 | select count(*) from t |
| 3 | 0.00004200 | show prifile for query 2 |
| 4 | 34.30410100 | insert into t(username) select username from t |
| 5 | 1.50563800 | select count(*) from t |
| 6 | 44.82054700 | update t set username = 'waill' |
+----------+-------------+------------------------------------------------+
6 rows in set (0.00 sec)
MySQL> show profile cpu,block io,memory,swaps,context switches,source for query 6;
+----------------------+-----------+-----------+------------+-------------------+---------------------+--------------+---------------+-------+-----------------------+---------------+-------------+
| Status | Duration | CPU_user | CPU_system | Context_voluntary | Context_involuntary | Block_ops_in | Block_ops_out | Swaps | Source_function | Source_file | Source_line |
+----------------------+-----------+-----------+------------+-------------------+---------------------+--------------+---------------+-------+-----------------------+---------------+-------------+
| (initialization) | 0.000035 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | check_Access | sql_parse.cc | 5306 |
| checking permissions | 0.000011 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | open_tables | sql_base.cc | 2629 |
| Opening tables | 0.000011 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_lock_tables | lock.cc | 153 |
| System lock | 0.000007 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_lock_tables | lock.cc | 162 |
| Table lock | 0.000008 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_update | sql_update.cc | 167 |
| init | 0.000021 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_update | sql_update.cc | 429 |
| Updating | 44.514679 | 27.976747 | 2.818571 | 9949 | 1584 | 0 | 0 | 0 | MySQL_update | sql_update.cc | 560 |
| end | 0.305671 | 0.028996 | 0.023997 | 43 | 18 | 0 | 0 | 0 | MySQL_execute_command | sql_parse.cc | 5122 |
| query end | 0.000026 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MySQL_parse | sql_parse.cc | 6116 |
| freeing items | 0.000016 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | dispatch_command | sql_parse.cc | 2146 |
| closing tables | 0.000012 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | log_slow_statement | sql_parse.cc | 2204 |
| logging slow query | 0.00005 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | dispatch_command | sql_parse.cc | 2169 |
+----------------------+-----------+-----------+------------+-------------------+---------------------+--------------+---------------+-------+-----------------------+---------------+-------------+
