Difference between revisions of "MariaDB/MySQL"
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=Set up replication= | =Set up replication= | ||
With replication all transactions on the master database server are immediately replicated to the slave database server. So you create a hot copy of the database that can be used in case of a failure of the master server or to offload the master server by executing retrieval queries on the slave. | With replication all transactions on the master database server are immediately replicated to the slave database server. So you create a hot copy of the database that can be used in case of a failure of the master server or to offload the master server by executing retrieval queries on the slave. | ||
+ | |||
+ | The slave server logs into the master and checks if the bin-log position differs, if so all transactions after the last binlog-position are redone on the slave. | ||
This procedure is for a large part based on a tutorial found on howtoforge.com [https://www.howtoforge.com/mysql_database_replication] | This procedure is for a large part based on a tutorial found on howtoforge.com [https://www.howtoforge.com/mysql_database_replication] |
Revision as of 12:59, 2 January 2022
MariaDB is an open source fork of MySQL. There are some differences but most are internal, for users the commands and SQL syntax is exactly the same.
phpMyAdmin is a web based GUI for the maintenance of MariaDB and MySQL servers.
- show status like 'Qcache_total_blocks'
- Fragmentation of the query cache (lower is better)
- flush query cache
- Flush the query cache to fix the fragmentation (check if cache sizes need to be changed too)
User management
- alter user username@host identified by 'password'
- Change a users password
- drop user username@host
- Delete a user
- grans all privileges on *.* to 'user'@'host';
- Grant all privileges to all database to a user
Move users from one server to another
Starting on the source server execute this script
PASSWORD=$1
mysql -B -N -uroot -p${PASSWORD} -e "SELECT CONCAT('\'', user,'\'@\'', host, '\'') FROM user WHERE user IN ('username1', 'username2', 'username3')" > users.txt
while read line
do
mysql -B -N -uroot -p${PASSWORD} -e "SHOW GRANTS FOR $line"
done < users.txt > users.sql
sed -i 's/$/;/' users.sql
Move the file to the other server and there do:
mysql -u root -p < users.sql
Set up replication
With replication all transactions on the master database server are immediately replicated to the slave database server. So you create a hot copy of the database that can be used in case of a failure of the master server or to offload the master server by executing retrieval queries on the slave.
The slave server logs into the master and checks if the bin-log position differs, if so all transactions after the last binlog-position are redone on the slave.
This procedure is for a large part based on a tutorial found on howtoforge.com [1]
On the master
- Edit the my.cnf so it has below lines.
- The server must be accessible from the slave server and the server-id must be unique in you network
- The binlog-do-db specifies for which database the binlog is written, one line per database. If omitted for all databases binlog is written which is the easiest setup.
#skip-networking #bind-address = 127.0.0.1 log-bin = /var/log/mysql/mysql-bin.log #binlog-do-db=exampledb server-id=1
- Restart the database server
/etc/init.d/mysql restart
- Create a replication user
mysql -uroot -p mysql> GRANT REPLICATION SLAVE ON *.* TO 'slave_user'@'%' IDENTIFIED BY '<some_password>'; mysql> FLUSH PRIVILEGES;
mysql> USE exampledb; mysql> FLUSH TABLES WITH READ LOCK; mysql> SHOW MASTER STATUS; +---------------+----------+--------------+------------------+ | File | Position | Binlog_do_db | Binlog_ignore_db | +---------------+----------+--------------+------------------+ | mysql-bin.006 | 183 | | | +---------------+----------+--------------+------------------+ 1 row in set (0.00 sec)
- Dump the database
mysqldump -u root -p<password> --opt exampledb > exampledb.sql
- Unlock the tables
mysql -u root -p<password> mysql>UNLOCK TABLES; mysql> quit;
On the slave server
- Create the slave database
mysql -u root -p mysql> CREATE DATABASE exampledb; mysql> quit;
- Load the database dump created on the master
mysql -u root -p<password> exampledb < /path/to/exampledb.sql
- Edit the my.cnf so it has these lines
- The server-id must be unique in you network
- The replicate-do-db specifies for which database the binlog on the master is read, one line per database. If omitted for all databases binlog is read.
server-id=2 replicate-do-db=exampledb
- Restart the database server
/etc/init.d/mysql restart
In the following statement the values from SHOW MASTER STATUS above must be used.
mysql -u root -p<password> mysql> STOP SLAVE; mysql> CHANGE MASTER TO MASTER_HOST=<masterIP>, MASTER_USER='slave_user', MASTER_PASSWORD='<password>', MASTER_LOG_FILE='mysql-bin.006', MASTER_LOG_POS=183; mysql> START SLAVE; mysql> quit;
Repair replication
On the slave server
- Stop replication processes
mysql -u root -p mysql> stop slave;
On the master server
Dump the replicated databases including the replication data.
mysqldump --databases <db1> <db2> --master-data=1 > ../mysql_dump_$(hostname)_$(date +%Y-%m-%d_%H-%M).sql.dump
On the slave server
- Import the databases
mysql -uroot -p < <mysql_dump_...sql.dump
- Restart the slave processes and check the slave status.
mysql -u root -p mysql> start slave; mysql> show slave status \G
Populate and update timezone information
Timezone information is required to use functions like CONVERT_TZ. The mysql.time_zone table need to be populated and maintained when the data changes.
On a synology server following command takes care of this:
/volume1/@appstore/MariaDB10/usr/local/mariadb10/bin/mysql_tzinfo_to_sql /usr/share/zoneinfo |mysql -uroot -p mysql