query_cache_size

The MySQL query cache will cache the result sets of your queries, serving them instead of executing the same queries again. According to MySQL, “Searches for a single row in a single-row table are 238% faster with the query cache than without it.” For a query to return a cached result it must match the cached query exactly, in terms of case and whitespace, and it must not contain subqueries (read this article about Rewriting Subqueries as Joins). This is disabled by default in MySQL, so be sure to enable it first. I set it to 64MB.

query-cache-type = 1
query_cache_size = 64M

key_buffer_size / innodb_buffer_pool_size

The key buffer size is the amount of memory allocated to store table indexes, which can considerably speed up a query as searching for which rows to retrieve may require no disk access. innodb_buffer_pool_size is the innoDB implementation of this setting. On dedicated MySQL servers it is recommended to set this to 75% of the amount of RAM installed. I set key_buffer_size to 256MB as we have few MyISAM tables, and innodb_buffer_pool_size to 1GB so Apache and other services were not adversely affected.

key_buffer_size = 256M
innodb_buffer_pool_size = 1G

table_cache

The table cache is the number of tables that will be stored in memory at once, each table being stored in the cache as MySQL accesses it. I set it to 256.

table_cache = 256

helpful apps

MySQL Report will return information on how your server is currently performing and a list of some of the more useful variables. Get MySQL Report here, and get a guide to understand the report here.

MySQL Tuner will analyse your server and provide recommendations as to how different MySQL settings could be altered and any problems that could result from the current configuration. Get MySQL Tuner here.

$user = 'YOUR_USER';
$password = 'YOUR_PASSWORD';
$host = 'YOUR_HOST';
$backup_dir = '/path_to_backup_dir/'.date('YmdHis');

//mysqldump commands
$default_mysqldump_shared_command = 'mysqldump --force --user='.$user.' --password='.$password.' --host='.$host.' --quote-names --default-character-set=utf8 --verbose --compress';
$default_mysqldump_innodb_command = $default_mysqldump_shared_command.' --single-transaction --skip-add-locks --skip-lock-tables';
$default_mysqldump_myisam_command = $default_mysqldump_shared_command.' --opt';

//connect
set_time_limit(0);
if(!mysql_connect($host, $user, $password))
	exit;

//create backup dir
shell_exec('mkdir '.$backup_dir);

//cycle through databases
$query = "SHOW DATABASES";
$database_result = mysql_query($query);
while($database_data = mysql_fetch_array($database_result, MYSQL_ASSOC)) {
	//current db
	$current_database = $database_data['Database'];

	//create dir
	echo shell_exec('mkdir '.$backup_dir.'/'.$current_database);

	//get table list
	mysql_select_db($current_database);
	$query = "SHOW FULL TABLES WHERE Table_Type != 'VIEW'";
	$table_result = mysql_query($query);
	while($table_data = mysql_fetch_array($table_result, MYSQL_ASSOC)) {
		//current table
		$current_table = $table_data['Tables_in_'.$current_database];

		//get table type
		$query = "SHOW TABLE STATUS LIKE '{$current_table}'";
		$table_properties_result = mysql_query($query);
		$table_properties = mysql_fetch_array($table_properties_result, MYSQL_ASSOC);

		echo 'backing up '.$current_database.'.'.$current_table."\r\n";
		$success = false;
		while($success == false) {
			//innodb or not?
			if($table_properties['Engine'] == 'InnoDB')
				$result = shell_exec($default_mysqldump_innodb_command.' '.$current_database.' '.$current_table.'| gzip > '.$backup_dir.'/'.$current_database.'/'.$current_table.'.gz')."\r\n";
			else
				$result = shell_exec($default_mysqldump_myisam_command.' '.$current_database.' '.$current_table.'| gzip > '.$backup_dir.'/'.$current_database.'/'.$current_table.'.gz')."\r\n";

			//error
			if(strpos($result, 'Error 2013') !== false)
				echo 'lost connection, trying again'."\r\n";
			else
				$success = true;
		}
	}
}