ERROR 1194 (HY000): Table 'user' is marked as crashed and should be repaired

Este problema sucede porque la base de datos de MySQL esta corrupta, ya sea por un problema en el disco, al matar el proceso de MySQL/MariaDB sin pararlo antes o similares.

shell> mysql

MariaDB>  SELECT * FROM mysql.user;
ERROR 1194 (HY000): Table 'user' is marked as crashed and should be repaired

Warning in .\libraries\classes\Dbal\DbiMysqli.php#240
 mysqli::query(): (HY000/126): Index for table '.\mysql\user.MYI' is corrupt; try to repair it

Para solucionar esto hacemos lo siguiente:

1. Comprobar el estado de la DB:

En este caso se ve que mi tabla esta corrupta.  "Corrupt"

shell> mysql -u root -p
MariaDB [(none)]> CHECK TABLE mysql.user;
+------------+-------+----------+-----------------------------------------------------------------+
| Table      | Op    | Msg_type | Msg_text                                                        |
+------------+-------+----------+-----------------------------------------------------------------+
| mysql.user | check | warning  | Size of indexfile is: 5628      Should be: 4096                 |
| mysql.user | check | warning  | Size of datafile is: 5012       Should be: 244                  |
| mysql.user | check | error    | Can't read indexpage from filepos: 2048                         |
| mysql.user | check | Error    | Index for table '.\mysql\user.MYI' is corrupt; try to repair it |
| mysql.user | check | error    | Corrupt                                                         |
+------------+-------+----------+-----------------------------------------------------------------+
5 rows in set (0.00 sec)

2. Reparar la base de datos:  Mysql.User

MariaDB [(none)]> REPAIR TABLE mysql.user;
+------------+--------+----------+--------------------------------------------------+
| Table      | Op     | Msg_type | Msg_text                                         |
+------------+--------+----------+--------------------------------------------------+
| mysql.user | repair | info     | Wrong bytesec:  50- 48- 50 at 0; Skipped         |
| mysql.user | repair | info     | Found block that points outside data file at 92  |
| mysql.user | repair | info     | Found block that points outside data file at 96  |
| mysql.user | repair | info     | Found block that points outside data file at 100 |
| mysql.user | repair | info     | Found block that points outside data file at 104 |
| mysql.user | repair | info     | Found block that points outside data file at 108 |
| mysql.user | repair | info     | Found block that points outside data file at 112 |
| mysql.user | repair | info     | Wrong bytesec:  50- 48- 50 at 244; Skipped       |
| mysql.user | repair | warning  | Number of rows changed from 4 to 2               |
| mysql.user | repair | status   | OK                                               |
+------------+--------+----------+--------------------------------------------------+
10 rows in set (0.00 sec)

3. Volvemos a comprobar el estado de la base de datos:

MariaDB [(none)]> CHECK TABLE mysql.user;
+------------+-------+----------+----------+
| Table      | Op    | Msg_type | Msg_text |
+------------+-------+----------+----------+
| mysql.user | check | status   | OK       |
+------------+-------+----------+----------+
1 row in set (0.00 sec)

4. Reiniciamos el servicio de MySQL / MariaDB

Después de reiniciar el servidor ya debería de desaparecer este problema.

Nota: En algunos casos debemos hacer los mismos pasos para la base de datos principal de MySQL:

shell> mysql -u root -p
MariaDB [(none)]> CHECK TABLE mysql.db;
MariaDB [(none)]> REPAIR TABLE mysql.db;
MariaDB [(none)]> CHECK TABLE mysql.db;