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MySQL 5.0 Reference Manual :: D Portar a otros sistemas :: D.1 Depurar un servidor MySQL :: D.1.5 El uso de registros (logs) para encontrar la causa de errores de mysqld
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D.1.5. El uso de registros (logs) para encontrar la causa de errores de mysqld

Note that before starting mysqld with --log you should check all your tables with myisamchk. See Capítulo 5, Administración de bases de datos.

If mysqld dies or hangs, you should start mysqld with --log. When mysqld dies again, you can examine the end of the log file for the query that killed mysqld.

If you are using --log without a file name, the log is stored in the database directory as host_name.log In most cases it is the last query in the log file that killed mysqld, but if possible you should verify this by restarting mysqld and executing the found query from the mysql command-line tools. If this works, you should also test all complicated queries that didn't complete.

You can also try the command EXPLAIN on all SELECT statements that takes a long time to ensure that mysqld is using indexes properly. See Sección 7.2.1, “Sintaxis de EXPLAIN (Obtener información acerca de un SELECT)”.

You can find the queries that take a long time to execute by starting mysqld with --log-slow-queries. See Sección 5.10.4, “El registro de consultas lentas (Slow Query Log)”.

If you find the text mysqld restarted in the error log file (normally named hostname.err) you probably have found a query that causes mysqld to fail. If this happens, you should check all your tables with myisamchk (see Capítulo 5, Administración de bases de datos), and test the queries in the MySQL log files to see if one doesn't work. If you find such a query, try first upgrading to the newest MySQL version. If this doesn't help and you can't find anything in the mysql mail archive, you should report the bug to a MySQL mailing list. The mailing lists are described at http://lists.mysql.com/, which also has links to online list archives.

If you have started mysqld with myisam-recover, MySQL automatically checks and tries to repair MyISAM tables if they are marked as 'not closed properly' or 'crashed'. If this happens, MySQL writes an entry in the hostname.err file 'Warning: Checking table ...' which is followed by Warning: Repairing table if the table needs to be repaired. If you get a lot of these errors, without mysqld having died unexpectedly just before, then something is wrong and needs to be investigated further. See Sección 5.3.1, “Opciones del comando mysqld”.

It's not a good sign if mysqld did die unexpectedly, but in this case one shouldn't investigate the Checking table... messages but instead try to find out why mysqld died.

Ésta es una traducción del manual de referencia de MySQL, que puede encontrarse en dev.mysql.com. El manual de referencia original de MySQL está escrito en inglés, y esta traducción no necesariamente está tan actualizada como la versión original. Para cualquier sugerencia sobre la traducción y para señalar errores de cualquier tipo, no dude en dirigirse a mysql-es@vespito.com.