MySQL source code: thought of by the query_response_time_stats Parameter

Percona provides the query_response_time_stats parameter to observe the database Response Time on the server side.Root @ test 02:29:35> show variables like 'query _ response_time_stats ';

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

| Variable_name | Value |

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

| Query_response_time_stats | OFF |

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

1 row in set (0.00 sec)

 

Set this global variable to 'on' to observe the response time.

Root @ test 02:29:47> set globalquery_response_time_stats = 'on ';

Query OK, 0 rows affected (0.00 sec)

 

The response time information is recorded in a built-in I _S plug-in: QUERY_RESPONSE_TIME. Its structure is as follows and contains three fields:

Root @ information_schema 02:56:37> desc QUERY_RESPONSE_TIME;

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

| Field | Type | Null | Key | Default | Extra |

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

| Time | varchar (14) | NO |

| Count | int (11) unsigned | NO | 0 |

| Total | varchar (14) | NO |

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

3 rows in set (0.00 sec)

 

Root @ information_schema 04:28:01> select * from QUERY_RESPONSE_TIME;

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

| Time | count | total |

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

| 0.000001 | 0 | 0.000000 |

| 0.000010 | 0 | 0.000000 |

| 1, 0.000100 | 16 | 0.000697 |

| 0.001000 | 11 | 0.002144 |

| 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 |

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

 

Time indicates the RT interval (you can set it by the query_response_time_range_base parameter). count indicates the number of SQL statements collected in the interval, and total indicates the total execution time of these SQL statements.

This I _s table is implemented in the Code SQL/query_response_time.cc. Initialize (empty function) at system startup (init_server_components function) and declare the built-in I _s table in SQL _show.cc

Field definition:

ST_FIELD_INFO query_response_time_fields_info []

The definition in the I _s table description array (ST_SCHEMA_TABLEschema_tables []) is as follows:

# Ifdef HAVE_RESPONSE_TIME_DISTRIBUTION

{"QUERY_RESPONSE_TIME", query_response_time_fields_info, create_schema_table,

Query_response_time_fill, make_old_format, 0,-1,-1, 0, 0 },

# Else

{"QUERY_RESPONSE_TIME", query_response_time_fields_info, create_schema_table,

0, make_old_format, 0,-1,-1, 0, 0 },

# Endif // HAVE_RESPONSE_TIME_DISTRIBUTION

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