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Category Archives: MySQL

How To Move MySQL Data Directory (datadir)

Create a directory in the drive you want to store MySQL datadir. In this example, we create mysql folder in /backup partition. Now we have MySQL data copied, but we don’t have all data as MySQL service is running and

configure: error: libmysqlclient is needed for MySQL support

When i install pureftpd with mysql support on CentOS 7 server, i get following error This is because MySql dev packages are missing on the server. Fixed by installing

Repair MySQL MyISAM Database with myisamchk

myisamchk is a command line tool to repair MySQL MyISAM database. You need to run it a user root. To repair all MyISAM tables in a database, run Example [root@localhost ~]# myisamchk –recover /var/lib/mysql/w3blogs/wp_blogs – recovering (with sort) MyISAM-table ‘/var/lib/mysql/w3blogs/wp_blogs’

MySQL Slow Query Log

MySQL Slow Query Log i used to find SQL query that are slow. To enable Slow Query Log, add following to /etc/my.cnf file under [mysqld] section. If you don’ have folder /var/log/mysql/, create it Now restart MySQL or

InnoDB: mmap(x bytes) failed; errno 12

On a VPS, MariaDB refused to start with error [root@ip-10-0-51-171 mariadb]# service mariadb start Redirecting to /bin/systemctl start mariadb.service Job for mariadb.service failed because the control process exited with error code. See “systemctl status mariadb.service” and “journalctl -xe” for details.

Repair MySQL database with mysqlcheck

mysqlcheck command can be used to check, repair, optimize or analyzes tables in a MySQL database. To check a database for errors, run If you database need user name and password, specify it with -u USER-NAME -p, for example This

PHP can’t connect to MySQL running on localhost

On a server, PHP can’t connect to MySQL with following code, it returned error “Could not connect: Permission denied 2002” If i change “localhost” with IP address 127.0.0,1, PHP script is able to connect to MySQL server properly. If i

MySQL Configuration

Here are some of the configurations for MySQL, some of these are already set on your server. When you edit MySQL configuration file (/etc/my.cnf or /etc/mysql/my.cnf), you need to restart MySQL as it is only read when you start MySQL.

InnoDB Error log file ib_logfile0 is of different size

After copying MySQL data (/var/lib/mysql) folder from one server to another, MariaDB failed to start. On checking log, found following error InnoDB: Error: log file ./ib_logfile0 is of different size 0 268435456 bytes InnoDB: than specified in the .cnf file

MySQL Can’t open and lock privilege tables

Recently on of the server had its HDD failed. After moving MySQL data (/var/lib/mysql) to another server MySQL (MariaDB) would not start. On checking log file, i got following errors 170314 14:48:09 Percona XtraDB ( 5.5.49-MariaDB-38.0 started; log sequence number