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How To Find Queries Taking Longer Than N Seconds in MYSQL ?

2 min read
MySQL Server - Version 5.1 and later

The simplest way to find long running queries are to look at the process list. There are various options how to do this depending on your version and whether you have the Sys Schema installed.
The Sys Schema session View

In MySQL 5.6 or later with the Sys Schema installed, you can use the session view, for example:
mysql> SELECT * FROM sys.session WHERE command = 'Query' AND time > 10\G
*************************** 1. row ***************************
                thd_id: 36
               conn_id: 11
                  user: root@localhost
                    db: db1
               command: Query
                 state: copy to tmp table
                  time: 244
     current_statement: ALTER TABLE MegaCity ENGINE=InnoDB
     statement_latency: 4.06 m
              progress: 52.73
          lock_latency: 21.55 ms
         rows_examined: 0
             rows_sent: 0
         rows_affected: 0
            tmp_tables: 0
       tmp_disk_tables: 0
             full_scan: NO
        last_statement: NULL
last_statement_latency: NULL
        current_memory: 296.29 KiB
             last_wait: NULL
     last_wait_latency: NULL
                source: NULL
           trx_latency: NULL
             trx_state: NULL
        trx_autocommit: NULL
                   pid: 11884
          program_name: mysql
1 row in set (0.08 sec)
The session view is the same as the sys.processlist view with the difference that the session view excludes background threads.
The Performance Schema threads table

In MySQL 5.6 and later it is recommended to use the performance_schema.threads table over SHOW PROCESSLIST or the information_schema.PROCESSLIST as using the threads table has less impact on the running queries. The Sys Schema views processlist and session discussed above are built on top of the threads table. To get long running queries, you can for example use:
mysql> SELECT PROCESSLIST_ID, PROCESSLIST_USER, PROCESSLIST_HOST, PROCESSLIST_DB, PROCESSLIST_COMMAND, PROCESSLIST_TIME, PROCESSLIST_STATE, PROCESSLIST_INFO FROM performance_schema.threads WHERE PROCESSLIST_COMMAND = 'Query' AND PROCESSLIST_TIME > 10;
+----------------+------------------+------------------+----------------+---------------------+------------------+---------------------------+-------------------------------------------------+
| PROCESSLIST_ID | PROCESSLIST_USER | PROCESSLIST_HOST | PROCESSLIST_DB | PROCESSLIST_COMMAND | PROCESSLIST_TIME | PROCESSLIST_STATE         | PROCESSLIST_INFO                                |
+----------------+------------------+------------------+----------------+---------------------+------------------+---------------------------+-------------------------------------------------+
|             11 | root             | localhost        | db1            | Query               |               49 | Searching rows for update | UPDATE MegaCity SET Population = Population + 1 |
+----------------+------------------+------------------+----------------+---------------------+------------------+---------------------------+-------------------------------------------------+
1 row in set (0.00 sec)
The Information Schema PROCESSLIST table

In MySQL 5.1 and 5.5 the above solutions cannot be used. Instead use the PROCESSLIST table in the Information Schema. Querying the PROCESSLIST table is equivalent to executing SHOW PROCESSLIST with the difference that you can specify a WHERE clause.
mysql> SELECT * FROM information_schema.PROCESSLIST WHERE Command = 'Query' AND TIME > 10;
+----+------+-----------+------+---------+------+---------------------------+-------------------------------------------------+
| ID | USER | HOST      | DB   | COMMAND | TIME | STATE                     | INFO                                            |
+----+------+-----------+------+---------+------+---------------------------+-------------------------------------------------+
| 11 | root | localhost | db1  | Query   |   24 | Searching rows for update | UPDATE MegaCity SET Population = Population + 1 |
+----+------+-----------+------+---------+------+---------------------------+-------------------------------------------------+
1 row in set (0.00 sec)

Hope it worked !! šŸ™‚