Explain and profiling parsing query SQL time

MySQL can use the profiling command to see how long it takes to execute query SQL.

By default, MySQL is turned off by the profiling command:

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1. SELECT @ @profiling;

+-------------------+

| @ @profiling |

+-------------------+

| 0 |

+-------------------+

Description

0: Indicates that the profiling function is off;

1: Indicates open.

The profiling function can be turned on/off by command.

Open command:

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1. Set profiling=1;

Close command: [SQL]View PlainCopy

1. Set profiling=0;

such as query command:

SELECT * FROM Employee limit 1, 10;

You can use the profiling command to see how long it takes to execute this sql:

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1. Show Profiles;

Query Result:

+----------------+-----------------+-------------------------------------------------------------+

| query_id | Duration | Query |

+----------------+-----------------+--------------------------------------------------------------+

| 1 | 0.00083225 | SELECT * FROM Employee limit 1,10 |

+----------------+-----------------+--------------------------------------------------------------+

1 row in Set (0.00 sec)

Use explain to analyze whether a hit index

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2. mysql> explain select * from user where username = ' a ';
4. +----+-------------+-------+------+---------------+------------+---------+-------+------+-------------+  
6. | ID | Select_type | Table | type | possible_keys | Key | key_len | ref | Rows |  Extra |
8. +----+-------------+-------+------+---------------+------------+---------+-------+------+-------------+  
10. | 1 | Simple |    user | ref | user_index | user_index | 1 |  Using where |
12. +----+-------------+-------+------+---------------+------------+---------+-------+------+-------------+  
14. 1 row in Set (0.00 sec)

You can see that you have hit index User_index

Explain and profiling parsing query SQL time