Tag Archives: Base De Datos

Hace unos días tuvimos un corte de luz en nuestros servidores, y una tabla de la base de datos MySql quedo corrupta. Al intentar hacer una consulta sobre esa tabla, nos generaba el siguiente error de mysql:

Error Mysql 1030 Got error 134 from storage engine

Para solucionar esto, debemos reparar la tabla en cuestion ejecutando las siguientes consultas:

> check table NOMBRETABLA;

para ver los errores que tenemos en la tabla

> repair table NOMBRETABLA;

para solucionar los errores en esa tabla y dejar la tabla otra vez operativa.

Cuando un proyecto empieza a tener consistencia y a tener un numero alto de visitas, lo más normal es que la base de datos empieza a ralentizarse.

Para ello, como siempre hemos dicho, lo más importante es optimizar las consultas sql, que siempre se puede optimizar para un mejor aprovechamiento del tiempo de cpu usado por mysql.

Una vez hecho esto, hay que tomar ciertas medidas en la configuración de mysql para optimizar este motor de base de datos. Por defecto, no se aprovecha todo el potencial que tiene y según vamos necesitando, se debe modificar para optimizar este punto tambien.

Os adjunto el fichero my.cnf o my.conf que suele estár en /etc para optimizar vuestro mysql.

# Example MySQL config file for very large systems.
#
# This is for a large system with memory of 1G-2G where the system runs mainly
# MySQL.
#
# You can copy this file to
# /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options (in this
# installation this directory is /var/lib/mysql) or
# ~/.my.cnf to set user-specific options.
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the «–help» option.

# The following options will be passed to all MySQL clients
[client]
#password    = your_password
port        = 3306
socket        = /var/lib/mysql/mysql.sock

# Here follows entries for some specific programs

# The MySQL server
[mysqld]
port        = 3306
socket        = /var/lib/mysql/mysql.sock
skip-locking
key_buffer = 384M
#ax_allowed_packet = 1M
table_cache = 512
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size = 32M

# custom
old_passwords=1
log-slow-queries=/var/log/mysql-slow-queries.log
log-error=/var/log/mysqld.log
#set-variable = max_connections=500
max_connections = 512
wait_timeout = 15
max_user_connections = 200
max_allowed_packet = 16M
max_connect_errors = 200

# Try number of CPU’s*2 for thread_concurrency
thread_concurrency = 8

# Don’t listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the «enable-named-pipe» option) will render mysqld useless!
#
#skip-networking

# Replication Master Server (default)
# binary logging is required for replication
log-bin

# required unique id between 1 and 2^32 – 1
# defaults to 1 if master-host is not set
# but will not function as a master if omitted
server-id    = 1

# Replication Slave (comment out master section to use this)
#
# To configure this host as a replication slave, you can choose between
# two methods :
#
# 1) Use the CHANGE MASTER TO command (fully described in our manual) –
#    the syntax is:
#
#    CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
#    MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
#
#    where you replace <host>, <user>, <password> by quoted strings and
#    <port> by the master’s port number (3306 by default).
#
#    Example:
#
#    CHANGE MASTER TO MASTER_HOST=’125.564.12.1′, MASTER_PORT=3306,
#    MASTER_USER=’joe’, MASTER_PASSWORD=’secret’;
#
# OR
#
# 2) Set the variables below. However, in case you choose this method, then
#    start replication for the first time (even unsuccessfully, for example
#    if you mistyped the password in master-password and the slave fails to
#    connect), the slave will create a master.info file, and any later
#    change in this file to the variables’ values below will be ignored and
#    overridden by the content of the master.info file, unless you shutdown
#    the slave server, delete master.info and restart the slaver server.
#    For that reason, you may want to leave the lines below untouched
#    (commented) and instead use CHANGE MASTER TO (see above)
#
# required unique id between 2 and 2^32 – 1
# (and different from the master)
# defaults to 2 if master-host is set
# but will not function as a slave if omitted
#server-id       = 2
#
# The replication master for this slave – required
#master-host     =   <hostname>
#
# The username the slave will use for authentication when connecting
# to the master – required
#master-user     =   <username>
#
# The password the slave will authenticate with when connecting to
# the master – required
#master-password =   <password>
#
# The port the master is listening on.
# optional – defaults to 3306
#master-port     =  <port>
#
# binary logging – not required for slaves, but recommended
#log-bin

# Point the following paths to different dedicated disks
#tmpdir        = /tmp/
#log-update     = /path-to-dedicated-directory/hostname

# Uncomment the following if you are using BDB tables
#bdb_cache_size = 384M
#bdb_max_lock = 100000

# Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /var/lib/mysql/
#innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
#innodb_log_group_home_dir = /var/lib/mysql/
#innodb_log_arch_dir = /var/lib/mysql/
# You can set .._buffer_pool_size up to 50 – 80 %
# of RAM but beware of setting memory usage too high
#innodb_buffer_pool_size = 384M
innodb_buffer_pool_size = 1024M
innodb_additional_mem_pool_size = 20M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 100M
innodb_log_buffer_size = 8M
innodb_flush_log_at_trx_commit = 1
innodb_lock_wait_timeout = 50

[mysqldump]
quick
max_allowed_packet = 16M

[mysql]
no-auto-rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates

[isamchk]
key_buffer = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M

[myisamchk]
key_buffer = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout

Realizar una copia del fichero antiguo:

cp /etc/my.cnf /etc/my.cnf.back

modificar el fichero my.cnf con por el que os he puesto

y reiniciar la base de datos

/etc/rc.d/init.d/mysqld restart

Si todo va ok, tendreis vuestro motor de base de datos mysql mucho mas optimizado.