mysql.install

<?php


/**
 * @file
 * Install, update and uninstall functions for the mysql module.
 */

use Drupal\Core\Database\Database;
use Drupal\Core\Render\Markup;

/**
 * Implements hook_requirements().
 */
function mysql_requirements($phase) {
  $requirements = [];
  if ($phase === 'runtime') {
    // Test with MySql databases.
    if (Database::isActiveConnection()) {
      $connection = Database::getConnection();
      // Only show requirements when MySQL is the default database connection.
      if (!($connection->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      // has been replaced by "transaction_isolation".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();
      $tables_missing_primary_key = [];
      $tables = $connection->schema()
        ->findTables('%');
      foreach ($tables as $table) {
        $primary_key_column = Database::getConnection()->query("SHOW KEYS FROM {" . $table . "} WHERE Key_name = 'PRIMARY'")
          ->fetchAllAssoc('Column_name');
        if (empty($primary_key_column)) {
          $tables_missing_primary_key[] = $table;
        }
      }
      $description = [];
      if ($isolation_level == 'READ-COMMITTED') {
        if (empty($tables_missing_primary_key)) {
          $severity_level = REQUIREMENT_OK;
        }
        else {
          $severity_level = REQUIREMENT_ERROR;
        }
      }
      else {
        if ($isolation_level == 'REPEATABLE-READ') {
          $severity_level = REQUIREMENT_WARNING;
        }
        else {
          $severity_level = REQUIREMENT_ERROR;
          $description[] = t('This is not supported by Drupal.');
        }
        $description[] = t('The recommended level for Drupal is "READ COMMITTED".');
      }
      if (!empty($tables_missing_primary_key)) {
        $description[] = t('For this to work correctly, all tables must have a primary key. The following table(s) do not have a primary key: @tables.', [
          '@tables' => implode(', ', $tables_missing_primary_key),
        ]);
      }
      $description[] = t('See the <a href=":performance_doc">setting MySQL transaction isolation level</a> page for more information.', [
        ':performance_doc' => 'https://www.drupal.org/docs/system-requirements/setting-the-mysql-transaction-isolation-level',
      ]);
      $requirements['mysql_transaction_level'] = [
        'title' => t('Transaction isolation level'),
        'severity' => $severity_level,
        'value' => $isolation_level,
        'description' => Markup::create(implode(' ', $description)),
      ];
    }
  }
  return $requirements;
}