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<?php
namespace SMW\SQLStore\TableBuilder;
use SMW\MediaWiki\Database;
/**
* @license GNU GPL v2+
* @since 2.2
*
* @author Jeroen De Dauw < jeroendedauw@gmail.com >
* @author mwjames
*/
class TemporaryTableBuilder {
/**
* @var Database
*/
private $connection;
/**
* @var boolean
*/
private $autoCommitFlag = false;
/**
* @since 2.3
*
* @param Database $connection
*/
public function __construct( Database $connection ) {
$this->connection = $connection;
}
/**
* @see $smwgQTemporaryTablesWithAutoCommit
* @since 2.5
*
* @param boolean $autoCommitFlag
*/
public function setAutoCommitFlag( $autoCommitFlag ) {
$this->autoCommitFlag = (bool)$autoCommitFlag;
}
/**
* @since 2.5
*
* @param string $tableName
*/
public function create( $tableName ) {
if ( $this->autoCommitFlag ) {
$this->connection->setFlag( Database::AUTO_COMMIT );
}
$this->connection->query(
$this->getSQLCodeFor( $tableName ),
__METHOD__,
false
);
}
/**
* @since 2.5
*
* @param string $tableName
*/
public function drop( $tableName ) {
if ( $this->autoCommitFlag ) {
$this->connection->setFlag( Database::AUTO_COMMIT );
}
$this->connection->query(
"DROP TEMPORARY TABLE " . $tableName,
__METHOD__,
false
);
}
/**
* Get SQL code suitable to create a temporary table of the given name, used
* to store ids.
*
* MySQL can do that simply by creating new temporary tables. PostgreSQL first
* checks if such a table exists, so the code is ready to reuse existing tables
* if the code was modified to keep them after query answering. Also, PostgreSQL
* tables will use a RULE to achieve built-in duplicate elimination. The latter
* is done using INSERT IGNORE in MySQL.
*
* @param string $tableName
*
* @return string
*/
private function getSQLCodeFor( $tableName ) {
// PostgreSQL: no memory tables, use RULE to emulate INSERT IGNORE
if ( $this->connection->isType( 'postgres' ) ) {
// Remove any double quotes from the name
$tableName = str_replace( '"', '', $tableName );
return "DO \$\$BEGIN "
. " IF EXISTS(SELECT NULL FROM pg_tables WHERE tablename='{$tableName}' AND schemaname = ANY (current_schemas(true))) "
. " THEN DELETE FROM {$tableName}; "
. " ELSE "
. " CREATE TEMPORARY TABLE {$tableName} (id SERIAL); "
. " CREATE RULE {$tableName}_ignore AS ON INSERT TO {$tableName} WHERE (EXISTS (SELECT 1 FROM {$tableName} "
. " WHERE ({$tableName}.id = new.id))) DO INSTEAD NOTHING; "
. " END IF; "
. "END\$\$";
}
// MySQL_ just a temporary table, use INSERT IGNORE later
return "CREATE TEMPORARY TABLE " . $tableName . "( id INT UNSIGNED KEY ) ENGINE=MEMORY";
}
}
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