driver() === 'mysql' && $connection->getProvider() === 'mysql')) { return []; } $query = 'SELECT @@SESSION.tx_isolation'; // The database variable "tx_isolation" has been removed in MySQL v8.0.3 and // has been replaced by "transaction_isolation". // @see https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_tx_isolation // @see https://dev.mysql.com/doc/refman/8.0/en/added-deprecated-removed.html if (!$connection->isMariaDb() && version_compare($connection->version(), '8.0.2-AnyName', '>')) { $query = 'SELECT @@SESSION.transaction_isolation'; } $isolation_level = $connection->query($query)->fetchField(); $requirements['mysql_transaction_level'] = [ 'title' => t('Database Isolation Level'), 'severity' => $isolation_level === 'READ-COMMITTED' ? REQUIREMENT_OK : REQUIREMENT_WARNING, 'value' => $isolation_level, 'description' => t('For the best performance and to minimize locking issues, the READ-COMMITTED transaction isolation level is recommended. See the setting MySQL transaction isolation level page for more information.', [ ':performance_doc' => 'https://www.drupal.org/docs/system-requirements/setting-the-mysql-transaction-isolation-level', ]), ]; } } return $requirements; }