113 lines
4.6 KiB
PHP
113 lines
4.6 KiB
PHP
<?php
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// $Id$
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/**
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* @file
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* Database interface code for MySQL database servers.
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*/
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/**
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* @ingroup database
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* @{
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*/
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class DatabaseConnection_mysql extends DatabaseConnection {
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public function __construct(array $connection_options = array()) {
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// This driver defaults to non transaction support.
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$this->transactionSupport = !empty($connection_options['transactions']);
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// MySQL never supports transactional DDL.
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$this->transactionalDDLSupport = FALSE;
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// Default to TCP connection on port 3306.
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if (empty($connection_options['port'])) {
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$connection_options['port'] = 3306;
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}
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$dsn = 'mysql:host=' . $connection_options['host'] . ';port=' . $connection_options['port'] . ';dbname=' . $connection_options['database'];
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parent::__construct($dsn, $connection_options['username'], $connection_options['password'], array(
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// So we don't have to mess around with cursors and unbuffered queries by default.
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PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
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// Because MySQL's prepared statements skip the query cache, because it's dumb.
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PDO::ATTR_EMULATE_PREPARES => TRUE,
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// Force column names to lower case.
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PDO::ATTR_CASE => PDO::CASE_LOWER,
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));
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// Force MySQL to use the UTF-8 character set by default.
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$this->exec('SET NAMES "utf8"');
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// Force MySQL's behavior to conform more closely to SQL standards.
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// This allows Drupal to run almost seamlessly on many different
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// kinds of database systems. These settings force MySQL to behave
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// the same as postgresql, or sqlite in regards to syntax interpretation
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// and invalid data handling. See http://drupal.org/node/344575 for further disscussion.
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$this->exec("SET sql_mode='ANSI,TRADITIONAL'");
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}
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public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
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return $this->query($query . ' LIMIT ' . $from . ', ' . $count, $args, $options);
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}
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public function queryTemporary($query, array $args = array(), array $options = array()) {
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$tablename = $this->generateTemporaryTableName();
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$this->query(preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE {' . $tablename . '} Engine=MEMORY SELECT', $query), $args, $options);
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return $tablename;
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}
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public function driver() {
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return 'mysql';
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}
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public function databaseType() {
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return 'mysql';
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}
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public function mapConditionOperator($operator) {
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// We don't want to override any of the defaults.
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return NULL;
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}
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public function nextId($existing_id = 0) {
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static $shutdown_registered = FALSE;
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$new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
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// This should only happen after an import or similar event.
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if ($existing_id >= $new_id) {
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// If we INSERT a value manually into the sequences table, on the next
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// INSERT, MySQL will generate a larger value. However, there is no way
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// of knowing whether this value already exists in the table. MySQL
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// provides an INSERT IGNORE which would work, but that can mask problems
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// other than duplicate keys. Instead, we use INSERT ... ON DUPLICATE KEY
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// UPDATE in such a way that the UPDATE does not do anything. This way,
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// duplicate keys do not generate errors but everything else does.
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$this->query('INSERT INTO {sequences} (value) VALUES (:value) ON DUPLICATE KEY UPDATE value = value', array(':value' => $existing_id));
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$new_id = $this->query('INSERT INTO {sequences} () VALUES ()', array(), array('return' => Database::RETURN_INSERT_ID));
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}
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if (!$shutdown_registered) {
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register_shutdown_function(array(get_class($this), 'nextIdDelete'));
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$shutdown_registered = TRUE;
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}
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return $new_id;
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}
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public static function nextIdDelete() {
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// While we want to clean up the table to keep it up from occupying too
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// much storage and memory, we must keep the highest value in the table
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// because InnoDB uses an in-memory auto-increment counter as long as the
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// server runs. When the server is stopped and restarted, InnoDB
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// reinitializes the counter for each table for the first INSERT to the
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// table based solely on values from the table so deleting all values would
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// be a problem in this case. Also, TRUNCATE resets the auto increment
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// counter.
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$max_id = db_query('SELECT MAX(value) FROM {sequences}')->fetchField();
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// We know we are using MySQL here, so need for the slower db_delete().
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db_query('DELETE FROM {sequences} WHERE value < :value', array(':value' => $max_id));
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}
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}
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/**
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* @} End of "ingroup database".
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*/
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