diff -u b/core/includes/database.inc b/core/includes/database.inc
--- b/core/includes/database.inc
+++ b/core/includes/database.inc
@@ -53,9 +53,7 @@
  * @see \Drupal\Core\Database\Connection::defaultOptions()
  */
 function db_query($query, array $args = [], array $options = []) {
-  $target = empty($options['target']) ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->query($query, $args, $options);
+  return Database::getConnection(Database::getTarget($options))->query($query, $args, $options);
 }
 
 /**
@@ -90,9 +88,7 @@
  */
 function db_query_range($query, $from, $count, array $args = [], array $options = []) {
   @trigger_error('db_query_range() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call queryRange() on it. For example, $injected_database->queryRange($query, $from, $count, $args, $options). See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->queryRange($query, $from, $count, $args, $options);
+  return Database::getConnection(Database::getTarget($options))->queryRange($query, $from, $count, $args, $options);
 }
 
 /**
@@ -125,9 +121,7 @@
  */
 function db_query_temporary($query, array $args = [], array $options = []) {
   @trigger_error('db_query_temporary() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call queryTemporary() on it. For example, $injected_database->queryTemporary($query, $args, $options). See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->queryTemporary($query, $args, $options);
+  return Database::getConnection(Database::getTarget($options))->queryTemporary($query, $args, $options);
 }
 
 /**
@@ -151,9 +145,7 @@
  */
 function db_insert($table, array $options = []) {
   @trigger_error('db_insert() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call insert() on it. For example, $injected_database->insert($table, $options); See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) || $options['target'] == 'replica' ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->insert($table, $options);
+  return Database::getConnection(Database::getTarget($options, 'default', ['replica']))->insert($table, $options);
 }
 
 /**
@@ -177,9 +169,7 @@
  */
 function db_merge($table, array $options = []) {
   @trigger_error('db_merge() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call merge() on it. For example, $injected_database->merge($table, $options). See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) || $options['target'] == 'replica' ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->merge($table, $options);
+  return Database::getConnection(Database::getTarget($options, 'default', ['replica']))->merge($table, $options);
 }
 
 /**
@@ -203,9 +193,7 @@
  */
 function db_update($table, array $options = []) {
   @trigger_error('db_update() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call call update() on it. For example, $injected_database->update($table, $options); See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) || $options['target'] == 'replica' ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->update($table, $options);
+  return Database::getConnection(Database::getTarget($options, 'default', ['replica']))->update($table, $options);
 }
 
 /**
@@ -229,9 +217,7 @@
  */
 function db_delete($table, array $options = []) {
   @trigger_error('db_delete is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call delete() on it. For example, $injected_database->delete($table, $options). See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) || $options['target'] == 'replica' ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->delete($table, $options);
+  return Database::getConnection(Database::getTarget($options, 'default', ['replica']))->delete($table, $options);
 }
 
 /**
@@ -255,9 +241,7 @@
  */
 function db_truncate($table, array $options = []) {
   @trigger_error('db_truncate() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call truncate() on it. For example, $injected_database->truncate($table, $options). See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) || $options['target'] == 'replica' ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->truncate($table, $options);
+  return Database::getConnection(Database::getTarget($options, 'default', ['replica']))->truncate($table, $options);
 }
 
 /**
@@ -285,9 +269,7 @@
  */
 function db_select($table, $alias = NULL, array $options = []) {
   @trigger_error('db_select() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call call select() on it. For example, $injected_database->db_select($table, $alias, $options); See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) ? 'default' : $options['target'];
-  unset($options['target']);
-  return Database::getConnection($target)->select($table, $alias, $options);
+  return Database::getConnection(Database::getTarget($options))->select($table, $alias, $options);
 }
 
 /**
@@ -312,8 +294,7 @@
  */
 function db_transaction($name = NULL, array $options = []) {
   @trigger_error('db_transaction is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Instead, get a database connection injected into your service from the container and call startTransaction() on it. For example, $injected_database->startTransaction($name). See https://www.drupal.org/node/2993033', E_USER_DEPRECATED);
-  $target = empty($options['target']) ? 'default' : $options['target'];
-  return Database::getConnection($target)->startTransaction($name);
+  return Database::getConnection(Database::getTarget($options))->startTransaction($name);
 }
 
 /**
@@ -452,8 +433,7 @@
  */
 function db_close(array $options = []) {
   @trigger_error('db_close() is deprecated in Drupal 8.0.x and will be removed before Drupal 9.0.0. Use \Drupal\Core\Database\Database::closeConnection() instead. See https://www.drupal.org/node/2993033.', E_USER_DEPRECATED);
-  $target = empty($options['target']) ? NULL : $options['target'];
-  Database::closeConnection($target);
+  Database::closeConnection(Database::getTarget($options, NULL));
 }
 
 /**
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Database/Database.php
+++ b/core/lib/Drupal/Core/Database/Database.php
@@ -511,4 +511,39 @@ protected static function getDatabaseDriverNamespace(array $connection_info) {
     return 'Drupal\\Core\\Database\\Driver\\' . $connection_info['driver'];
   }
 
+  /**
+   * Get target helper.
+   *
+   * Helps get "target" database from the query options.
+   *
+   * @param array $options
+   *   An array of options to control how the query operates.
+   * @param string|null $default
+   *   The default database target name.
+   * @param string[] $default_aliases
+   *   Aliases for the target that should be recognized as a default target.
+   *   For cases like target "replica" that should be changed to the "default".
+   *
+   * @return mixed|string
+   *   The target database for the database connection.
+   */
+  public static function getTarget(array &$options, $default = 'default', array $default_aliases = []) {
+    if (empty($options['target'])) {
+      $target = $default;
+    }
+    else {
+      $target = $options['target'];
+      if (!empty($default_aliases)) {
+        foreach ($default_aliases as $alias) {
+          if ($target === $alias) {
+            $target = $default;
+            break;
+          }
+        }
+      }
+    }
+    unset($options['target']);
+    return $target;
+  }
+
 }