diff --git a/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
index 691a6ae..93a5529 100644
--- a/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -176,6 +176,14 @@ public function __construct(\PDO $connection, array $connection_options) {
     // Initialize and prepare the connection prefix.
     $this->setPrefix(isset($connection_options['prefix']) ? $connection_options['prefix'] : '');
 
+    if (!empty($connection_options['namespace'])) {
+      $this->setPrefix($connection_options['namespace'])
+
+    }
+    else {
+      @trigger_error('calling \Drupal\Core\Database\Connection::__construct() without namespace key is deprecated in drupal:9.1.0 and is removed from drupal:10.0.0. See https://www.drupal.org/project/drupal/issues/3112476', E_USER_DEPRECATED);
+    }
+
     // Set a Statement class, unless the driver opted out.
     if (!empty($this->statementClass)) {
       $connection->setAttribute(\PDO::ATTR_STATEMENT_CLASS, [$this->statementClass, [$this]]);
@@ -638,14 +646,18 @@ public function query($query, array $args = [], $options = []) {
       switch ($options['return']) {
         case Database::RETURN_STATEMENT:
           return $stmt;
+
         case Database::RETURN_AFFECTED:
           $stmt->allowRowCount = TRUE;
           return $stmt->rowCount();
+
         case Database::RETURN_INSERT_ID:
           $sequence_name = isset($options['sequence_name']) ? $options['sequence_name'] : NULL;
           return $this->connection->lastInsertId($sequence_name);
+
         case Database::RETURN_NULL:
           return NULL;
+
         default:
           throw new \PDOException('Invalid return directive: ' . $options['return']);
       }
@@ -770,6 +782,7 @@ protected function expandArguments(&$query, &$args) {
    *
    * @param string $class
    *   The class for which we want the potentially driver-specific class.
+   *
    * @return string
    *   The name of the class that should be used for this driver.
    */
@@ -1469,7 +1482,7 @@ public function commit() {
   abstract public function nextId($existing_id = 0);
 
   /**
-   * Prepares a statement for execution and returns a statement object
+   * Prepares a statement for execution and returns a statement object.
    *
    * Emulated prepared statements does not communicate with the database server
    * so this method does not check the statement.
@@ -1521,7 +1534,7 @@ public function quote($string, $parameter_type = \PDO::PARAM_STR) {
    * Extracts the SQLSTATE error from the PDOException.
    *
    * @param \Exception $e
-   *   The exception
+   *   The exception.
    *
    * @return string
    *   The five character error code.