Answer:

To show the current privileges of a MySQL user, you can use the SHOW GRANTS statement

E.g.

mysql> SHOW GRANTS;

+----------------------------------------------------------------------------------------------------------------------------------------+
| Grants for root@localhost                                                                                                              |
+----------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY PASSWORD '*****************************************' WITH GRANT OPTION |
+----------------------------------------------------------------------------------------------------------------------------------------+

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Answer:

Like in the shell, we can execute the command whoami to find out the current user name, we can use the function CURRENT_USER();

E.g.

mysql> SELECT CURRENT_USER();
+----------------+
| CURRENT_USER() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)

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Answer:

If you only connect to the MySQL server from localhost and you might want to disable TCP/IP networking feature so the server is more secure.

To do so, edit the MySQL configurations, e.g. /etc/my.cnf

..
skip-networking
..

Don't forget to restart MySQL to take effect.

# /sbin/service mysqld restart

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Answer:

In previous article, we have already discussed how to list the database size in your MySQL server.

But if you want to have a more detail view on an individual database, you can try the following (crazy) SQL.

SELECT s.schema_name,
CONCAT(IFNULL(ROUND((SUM(t.data_length)+SUM(t.index_length))
/1024/1024,2),0.00),"Mb") total_size,
CONCAT(IFNULL(ROUND(((SUM(t.data_length)+SUM(t.index_length))-SUM(t.data_free))/1024/1024,2),0.00),"Mb")

data_used,
CONCAT(IFNULL(ROUND(SUM(data_free)/1024/1024,2),0.00),"Mb") data_free,
IFNULL(ROUND((((SUM(t.data_length)+SUM(t.index_length))-SUM(t.data_free))
/((SUM(t.data_length)+SUM(t.index_length)))*100),2),0) pct_used,
COUNT(table_name) total_tables
FROM INFORMATION_SCHEMA.SCHEMATA s
LEFT JOIN INFORMATION_SCHEMA.TABLES t ON s.schema_name = t.table_schema
WHERE s.schema_name = "mydatabase"
GROUP BY s.schema_name
ORDER BY pct_used DESC\G

It will give you something like the following..

 schema_name: mydatabase
  total_size: 165.09Mb
   data_used: 12.09Mb
   data_free: 153.00Mb
    pct_used: 7.33
total_tables: 133

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Answer:

To change the temporary directory of your MySQL server to use a non-default directory, you can change the tmpdir parameter in your my.cnf

..
tmpdir = /data/tmp
..

Don't forget to change the permission of that temporary directory

# sudo chmod mysql:mysql /data/tmp

Then restart MySQL to take effect.

# /sbin/service mysqld restart

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Answer:

To alter all the tables in a given database in MySQL, e.g. change the storage engine, you can first generate the SQL statements using following method.

mysql> select CONCAT("Alter Table `", TABLE_SCHEMA,"`.`", TABLE_NAME, "` ENGINE = InnoDB") AS cmd from TABLES where TABLE_SCHEMA = "test";

It will print out the followings:

+----------------------------------------------------------------+
| cmd                                                            |
+----------------------------------------------------------------+
| Alter Table `test`.`foo`  ENGINE = InnoDB                      |
| Alter Table `test`.`bar`  ENGINE = InnoDB                      |
...

Then you can execute the above commands manually.

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Answer:

If you have enabled the binary log in your MySQL server, you need to be aware that the log will use up the space of your local disk space. Old binary logs are generally not needed and you can auto remove expired entries from the binary log.

To do so, edit the MySQL configurations, e.g. /etc/my.cnf

..
expire_logs_days        = 60
..

The above configuration will auto remove entries in the binary old if they are older than 60 days.

Don't forget to restart MySQL to take effect.

# /sbin/service mysqld restart

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Answer:

When the updates are received from a MySQL master to a slave, it will not be logged in the binary log of the slave server. Sometimes, you might want to enable it, for example, in order to setup a chained replication.

To do so, edit the MySQL configurations, e.g. /etc/my.cnf

..
log-slave-updates
..

Don't forget to restart MySQL to take effect.

# /sbin/service mysqld restart

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Answer:

In the previous article, we have discussed how to perform a hot backup on InnoDB with XtraBackup , but is it possible to zip the result directly to a file?

Sure, you can use the wrapper script came with the XtraBackup - innobackupex

For example, to backup and zip the result files to zipped files, you can use:

# innobackupex --stream=tar ./ | gzip - > backup.tar.gz

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Answer:

You can buy the official backup tool - "InnoDB Hot Backup" if you have the money. But you can also use the free alternative - the Percona XtraBackup

To download and install, you can refer to their web site: http://www.percona.com/docs/wiki/percona-xtrabackup:installation:binaries

To perform a quick and simple backup, you need:

# sudo xtrabackup --defaults-file=/etc/mysql/my.cnf --backup --target-dir=/tmp/backup --datadir=/var/lib/mysql

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