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<?php
/**
* @file
* Database interface code for MySQL database servers.
*/
/**
* @ingroup database
* @{
*/
class DatabaseConnection_mysql extends DatabaseConnection {
/**
* Flag to indicate if we have registered the nextID cleanup function.
*
* @var boolean
*/
protected $shutdownRegistered = FALSE;
public function __construct(array $connection_options = array()) {
// This driver defaults to transaction support, except if explicitly passed FALSE.
$this->transactionSupport = !isset($connection_options['transactions']) || ($connection_options['transactions'] !== FALSE);
// MySQL never supports transactional DDL.
$this->transactionalDDLSupport = FALSE;
$this->connectionOptions = $connection_options;
// The DSN should use either a socket or a host/port.
if (isset($connection_options['unix_socket'])) {
$dsn = 'mysql:unix_socket=' . $connection_options['unix_socket'];
}
else {
// Default to TCP connection on port 3306.
$dsn = 'mysql:host=' . $connection_options['host'] . ';port=' . (empty($connection_options['port']) ? 3306 : $connection_options['port']);
}
$dsn .= ';dbname=' . $connection_options['database'];
parent::__construct($dsn, $connection_options['username'], $connection_options['password'], array(
// So we don't have to mess around with cursors and unbuffered queries by default.
PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
// Because MySQL's prepared statements skip the query cache, because it's dumb.
PDO::ATTR_EMULATE_PREPARES => TRUE,
// Force column names to lower case.
PDO::ATTR_CASE => PDO::CASE_LOWER,
));
// Force MySQL to use the UTF-8 character set. Also set the collation, if a
// certain one has been set; otherwise, MySQL defaults to 'utf8_general_ci'
// for UTF-8.
if (!empty($connection_options['collation'])) {
$this->exec('SET NAMES utf8 COLLATE ' . $connection_options['collation']);
}
else {
$this->exec('SET NAMES utf8');
}
// Force MySQL's behavior to conform more closely to SQL standards.
// This allows Drupal to run almost seamlessly on many different
// kinds of database systems. These settings force MySQL to behave
// the same as postgresql, or sqlite in regards to syntax interpretation
// and invalid data handling. See http://drupal.org/node/344575 for
// further discussion. Also, as MySQL 5.5 changed the meaning of
// TRADITIONAL we need to spell out the modes one by one.
$this->exec("SET sql_mode='ANSI,STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER'");
}
public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
return $this->query($query . ' LIMIT ' . (int) $from . ', ' . (int) $count, $args, $options);
}
public function queryTemporary($query, array $args = array(), array $options = array()) {
$tablename = $this->generateTemporaryTableName();
$this->query(preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE {' . $tablename . '} Engine=MEMORY SELECT', $query), $args, $options);
return $tablename;
}
public function driver() {
return 'mysql';
}
public function databaseType() {
return 'mysql';
}
public function mapConditionOperator($operator) {
// We don't want to override any of the defaults.
return NULL;
}
public function nextId($existing_id = 0) {
$new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
// This should only happen after an import or similar event.
if ($existing_id >= $new_id) {
// If we INSERT a value manually into the sequences table, on the next
// INSERT, MySQL will generate a larger value. However, there is no way
// of knowing whether this value already exists in the table. MySQL
// provides an INSERT IGNORE which would work, but that can mask problems
// other than duplicate keys. Instead, we use INSERT ... ON DUPLICATE KEY
// UPDATE in such a way that the UPDATE does not do anything. This way,
// duplicate keys do not generate errors but everything else does.
$this->query('INSERT INTO {sequences} (value) VALUES (:value) ON DUPLICATE KEY UPDATE value = value', array(':value' => $existing_id));
$new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
}
if (!$this->shutdownRegistered) {
// Use register_shutdown_function() here to keep the database system
// independent of Drupal.
register_shutdown_function(array($this, 'nextIdDelete'));
$shutdownRegistered = TRUE;
}
return $new_id;
}
public function nextIdDelete() {
// While we want to clean up the table to keep it up from occupying too
// much storage and memory, we must keep the highest value in the table
// because InnoDB uses an in-memory auto-increment counter as long as the
// server runs. When the server is stopped and restarted, InnoDB
// reinitializes the counter for each table for the first INSERT to the
// table based solely on values from the table so deleting all values would
// be a problem in this case. Also, TRUNCATE resets the auto increment
// counter.
try {
$max_id = $this->query('SELECT MAX(value) FROM {sequences}')->fetchField();
// We know we are using MySQL here, no need for the slower db_delete().
$this->query('DELETE FROM {sequences} WHERE value < :value', array(':value' => $max_id));
}
// During testing, this function is called from shutdown with the
// simpletest prefix stored in $this->connection, and those tables are gone
// by the time shutdown is called so we need to ignore the database
// errors. There is no problem with completely ignoring errors here: if
// these queries fail, the sequence will work just fine, just use a bit
// more database storage and memory.
catch (PDOException $e) {
}
}
/**
* Overridden to work around issues to MySQL not supporting transactional DDL.
*/
protected function popCommittableTransactions() {
// Commit all the committable layers.
foreach (array_reverse($this->transactionLayers) as $name => $active) {
// Stop once we found an active transaction.
if ($active) {
break;
}
// If there are no more layers left then we should commit.
unset($this->transactionLayers[$name]);
if (empty($this->transactionLayers)) {
if (!PDO::commit()) {
throw new DatabaseTransactionCommitFailedException();
}
}
else {
// Attempt to release this savepoint in the standard way.
try {
$this->query('RELEASE SAVEPOINT ' . $name);
}
catch (PDOException $e) {
// However, in MySQL (InnoDB), savepoints are automatically committed
// when tables are altered or created (DDL transactions are not
// supported). This can cause exceptions due to trying to release
// savepoints which no longer exist.
//
// To avoid exceptions when no actual error has occurred, we silently
// succeed for MySQL error code 1305 ("SAVEPOINT does not exist").
if ($e->errorInfo[1] == '1305') {
// If one SAVEPOINT was released automatically, then all were.
// Therefore, we keep just the topmost transaction.
$this->transactionLayers = array('drupal_transaction' => 'drupal_transaction');
}
else {
throw $e;
}
}
}
}
}
}
/**
* @} End of "ingroup database".
*/
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