请问MYSQL有没有不输出query结果只输出query执行时间的方法?

Question

比如说我要测试select * from t1,t2的执行时间
两个TABLE都有上千万行,明显打印是不可能的
请问有没有办法不输出query结果只输出query执行时间的方法?

Answer 1

select count(*) from (select * from t1,t2);这样试一下，虽然会有 count(*)对测试结果有些影响。但基本上做对比测试应该可以了

Answer 2

mysql> set profiling=1
    -> ;
Query OK, 0 rows affected (0.02 sec)mysql> show profiles
    -> ;
Empty set (0.02 sec)mysql> select * from test;
+----+-------+---------+-----+
| id | class | name    | age |
+----+-------+---------+-----+
|  1 | A     | aaa     | 20  |
|  2 | A     | B       | 25  |
|  3 | B     | ddd     | 30  |
|  4 | C     | B       | 40  |
|  5 | B     | sssffff | 50  |
+----+-------+---------+-----+
5 rows in set (0.02 sec)mysql> show profile for query
    -> 1;
+--------------------+----------+
| Status             | Duration |
+--------------------+----------+
| starting           | 0.000147 |
| Opening tables     | 0.000024 |
| System lock        | 0.000010 |
| Table lock         | 0.000015 |
| init               | 0.000027 |
| optimizing         | 0.000007 |
| statistics         | 0.000019 |
| preparing          | 0.000012 |
| executing          | 0.000005 |
| Sending data       | 0.006949 |
| end                | 0.000009 |
| query end          | 0.000006 |
| freeing items      | 0.000097 |
| logging slow query | 0.000004 |
| cleaning up        | 0.000005 |
+--------------------+----------+
15 rows in set (0.03 sec)mysql> show profile cpu for query  1;
+--------------------+----------+----------+------------+
| Status             | Duration | CPU_user | CPU_system |
+--------------------+----------+----------+------------+
| starting           | 0.000147 |     NULL |       NULL |
| Opening tables     | 0.000024 |     NULL |       NULL |
| System lock        | 0.000010 |     NULL |       NULL |
| Table lock         | 0.000015 |     NULL |       NULL |
| init               | 0.000027 |     NULL |       NULL |
| optimizing         | 0.000007 |     NULL |       NULL |
| statistics         | 0.000019 |     NULL |       NULL |
| preparing          | 0.000012 |     NULL |       NULL |
| executing          | 0.000005 |     NULL |       NULL |
| Sending data       | 0.006949 |     NULL |       NULL |
| end                | 0.000009 |     NULL |       NULL |
| query end          | 0.000006 |     NULL |       NULL |
| freeing items      | 0.000097 |     NULL |       NULL |
| logging slow query | 0.000004 |     NULL |       NULL |
| cleaning up        | 0.000005 |     NULL |       NULL |
+--------------------+----------+----------+------------+
15 rows in set (0.00 sec)
mysql> show profiles;
+----------+------------+--------------------+
| Query_ID | Duration   | Query              |
+----------+------------+--------------------+
|        1 | 0.00733250 | select * from test |
+----------+------------+--------------------+
1 row in set (0.00 sec)

Answer 3

你要具体时间吗？好像目前还没有想explain那样的语句