InnoDB purge worker in mariadb processlist

Question

I just installed mariadb-server-10.3.10 in ubuntu16.04

When I do log in, and check processlist I found some connection with user "system user" and with command "Daemon".

+----+-------------+-----------+--------------+---------+------+--------------------------+------------------+----------+
| Id | User        | Host      | db           | Command | Time | State                    | Info             | Progress |
+----+-------------+-----------+--------------+---------+------+--------------------------+------------------+----------+
|  1 | system user |           | NULL         | Daemon  | NULL | InnoDB purge coordinator | NULL             |    0.000 |
|  2 | system user |           | NULL         | Daemon  | NULL | InnoDB purge worker      | NULL             |    0.000 |
|  3 | system user |           | NULL         | Daemon  | NULL | InnoDB purge worker      | NULL             |    0.000 |
|  4 | system user |           | NULL         | Daemon  | NULL | InnoDB purge worker      | NULL             |    0.000 |
|  5 | system user |           | NULL         | Daemon  | NULL | InnoDB shutdown handler  | NULL             |    0.000 |
| 45 | lalit       | localhost | NULL         | Query   |    0 | Init                     | show processlist |    0.000 |
+----+-------------+-----------+--------------+---------+------+--------------------------+------------------+----------+

And my query also taking much time, query executing in MySQL within 2 minutes it's taking around 10 minutes in MariaDB.

I am not understanding what wrong with MariaDB.

Please can explain what is those worker doing in the server?

Answer 1

Innodb Purge workers do innodb purge, just a guess:) They likely do not do much if you did not insert/delete/update into innodb tables, but do something if you did.

Your actual problem is the slow query, not the system user. There are other tools that handle that, EXPLAIN being the first one.