diff --git a/core/core.services.yml b/core/core.services.yml
index 5b0de75..5f0493e 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -19,6 +19,8 @@ parameters:
   http.response.debug_cacheability_headers: false
   factory.keyvalue.expirable:
     default: keyvalue.expirable.database
+  factory.keyvalue.sorted_set:
+    default: keyvalue.sorted_set.database
   filter_protocols:
     - http
     - https
@@ -384,6 +386,12 @@ services:
   keyvalue.expirable.database:
     class: Drupal\Core\KeyValueStore\KeyValueDatabaseExpirableFactory
     arguments: ['@serialization.phpserialize', '@database']
+  keyvalue.sorted_set:
+    class: Drupal\Core\KeyValueStore\KeyValueSortedSetFactory
+    arguments: ['@service_container', '%factory.keyvalue.sorted_set%']
+  keyvalue.sorted_set.database:
+    class: Drupal\Core\KeyValueStore\KeyValueDatabaseSortedSetFactory
+    arguments: ['@serialization.phpserialize', '@database']
   logger.factory:
     class: Drupal\Core\Logger\LoggerChannelFactory
     parent: container.trait
diff --git a/core/lib/Drupal/Core/KeyValueStore/DatabaseStorageSortedSet.php b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorageSortedSet.php
new file mode 100644
index 0000000..bbd56bd
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorageSortedSet.php
@@ -0,0 +1,131 @@
+<?php
+
+namespace Drupal\Core\KeyValueStore;
+
+use Drupal\Component\Serialization\SerializationInterface;
+use Drupal\Core\Database\Connection;
+
+/**
+ * Defines the default key/value implementation for sorted sets.
+ *
+ * This key/value store implementation uses the database to store key/value
+ * data in a sorted set.
+ */
+class DatabaseStorageSortedSet implements KeyValueStoreSortedSetInterface {
+
+  /**
+   * @var string
+   */
+  protected $collection;
+
+  /**
+   * @var \Drupal\Component\Serialization\SerializationInterface
+   */
+  protected $serializer;
+
+  /**
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * @var string
+   */
+  protected $table;
+
+  /**
+   * @param string $collection
+   *   The name of the collection holding key and value pairs.
+   * @param \Drupal\Component\Serialization\SerializationInterface $serializer
+   *   The serialization class to use.
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The database connection to use.
+   * @param string $table
+   *   The name of the SQL table to use, defaults to key_value_sorted.
+   */
+  public function __construct($collection, SerializationInterface $serializer, Connection $connection,  $table = 'key_value_sorted') {
+    $this->collection = $collection;
+    $this->serializer = $serializer;
+    $this->connection = $connection;
+    $this->table = $table;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function add($score, $member) {
+    $this->addMultiple(array(array($score => $member)));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function addMultiple(array $pairs) {
+    foreach ($pairs as $pair) {
+      foreach ($pair as $score => $member) {
+        $encoded_member = $this->serializer->encode($member);
+        $this->connection->merge($this->table)
+          ->fields(array(
+            'collection' => $this->collection,
+            'name' => $score,
+            'value' => $encoded_member,
+          ))
+          ->condition('collection', $this->collection)
+          ->condition('value', $encoded_member)
+          ->execute();
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCount() {
+    return $this->connection->select($this->table, 't')
+      ->condition('collection', $this->collection)
+      ->countQuery()
+      ->execute()
+      ->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRange($start, $stop = NULL) {
+    $query = $this->connection->select($this->table, 't')
+      ->fields('t', array('value'))
+      ->condition('collection', $this->collection)
+      ->condition('name', $start, '>=');
+
+    if ($stop !== NULL) {
+      $query->condition('name', $stop, '<=');
+    }
+    $result = $query->orderBy('name', 'ASC')->execute();
+
+    $values = array();
+    foreach ($result as $item) {
+      $values[] = $this->serializer->decode($item->value);
+    }
+    return $values;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMaxScore() {
+    $query = $this->connection->select($this->table);
+    $query->condition('collection', $this->collection, '=');
+    $query->addExpression('MAX(name)');
+    return $query->execute()->fetchField();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMinScore() {
+    $query = $this->connection->select($this->table);
+    $query->condition('collection', $this->collection, '=');
+    $query->addExpression('MIN(name)');
+    return $query->execute()->fetchField();
+  }
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueDatabaseSortedSetFactory.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueDatabaseSortedSetFactory.php
new file mode 100644
index 0000000..071a45d
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueDatabaseSortedSetFactory.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace Drupal\Core\KeyValueStore;
+
+use Drupal\Component\Serialization\SerializationInterface;
+use Drupal\Core\Database\Connection;
+
+/**
+ * Defines the key/value store factory for the database backend.
+ */
+class KeyValueDatabaseSortedSetFactory implements KeyValueSortedSetFactoryInterface {
+
+  /**
+   * The serialization class to use.
+   *
+   * @var \Drupal\Component\Serialization\SerializationInterface
+   */
+  protected $serializer;
+
+  /**
+   * The database connection.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * Constructs this factory object.
+   *
+   * @param \Drupal\Component\Serialization\SerializationInterface $serializer
+   *   The serialization class to use.
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The Connection object containing the key-value tables.
+   */
+  function __construct(SerializationInterface $serializer, Connection $connection) {
+    $this->serializer = $serializer;
+    $this->connection = $connection;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function get($collection) {
+    return new DatabaseStorageSortedSet($collection, $this->serializer, $this->connection);
+  }
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueSortedSetFactory.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueSortedSetFactory.php
new file mode 100644
index 0000000..70ef0bd
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueSortedSetFactory.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace Drupal\Core\KeyValueStore;
+
+/**
+ * Defines the key/value store factory.
+ */
+class KeyValueSortedSetFactory extends KeyValueFactory implements KeyValueSortedSetFactoryInterface {
+
+  const DEFAULT_SERVICE = 'keyvalue.sorted_set.database';
+
+  const SPECIFIC_PREFIX = 'keyvalue_sorted_set_service_';
+
+  const DEFAULT_SETTING = 'keyvalue_sorted_set_default';
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueSortedSetFactoryInterface.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueSortedSetFactoryInterface.php
new file mode 100644
index 0000000..415b888
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueSortedSetFactoryInterface.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Drupal\Core\KeyValueStore;
+
+/**
+ * Defines the sorted set key/value store factory interface.
+ */
+interface KeyValueSortedSetFactoryInterface {
+
+  /**
+   * Constructs a new sorted set key/value store for a given collection name.
+   *
+   * @param string $collection
+   *   The name of the collection holding key and value pairs.
+   *
+   * @return \Drupal\Core\KeyValueStore\KeyValueStoreSortedSetInterface
+   *   An sorted set key/value store implementation for the given $collection.
+   */
+  public function get($collection);
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreSortedSetInterface.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreSortedSetInterface.php
new file mode 100644
index 0000000..b59fe6f
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreSortedSetInterface.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace Drupal\Core\KeyValueStore;
+
+/**
+ * Defines the interface for sorted data in a key/value store.
+ *
+ * An example would be an index of items, which have an order, where the last
+ * item or a range of items may be required.
+ */
+interface KeyValueStoreSortedSetInterface {
+
+  /**
+   * @param float $score
+   *   The key for the item, for example microtime(), which can be used to
+   *   generate a sequential value.
+   * @param mixed $member
+   *   The value of the item.
+   */
+  public function add($score, $member);
+
+  /**
+   * @param array $pairs
+   *   An array of key/value pairs to add.
+   */
+  public function addMultiple(array $pairs);
+
+  /**
+   * @return float
+   *   The highest key in the collection.
+   */
+  public function getMaxScore();
+
+  /**
+   * @return float
+   *   The lowest key in the collection.
+   */
+  public function getMinScore();
+
+  /**
+   * @return integer
+   *   The number of items in a collection.
+   */
+  public function getCount();
+
+  /**
+   * @param float $start
+   *   The first key in the range.
+   * @param float $stop
+   *   The last key in the range.
+   *
+   * @return array
+   *   An array of items within the given range.
+   */
+  public function getRange($start, $stop = NULL);
+
+}
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 6dc2663..02e7738 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -993,6 +993,37 @@ function system_schema() {
     ),
   );
 
+  $schema['key_value_sorted'] = array(
+    'description' => 'Key-value list storage table.',
+    'fields' => array(
+      'collection' => array(
+        'description' => 'A named collection of key and value pairs.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      // KEY is an SQL reserved word, so use 'name' as the key's field name.
+      'name' => array(
+        'description' => 'The index or score key for the value.',
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'size' => 'big',
+      ),
+      'value' => array(
+        'description' => 'The value.',
+        'type' => 'blob',
+        'not null' => TRUE,
+        'size' => 'big',
+      ),
+    ),
+    'indexes' => array(
+      'collection_name' => array('collection', 'name'),
+      'name' => array('name'),
+    ),
+  );
+
   $schema['sequences'] = array(
     'description' => 'Stores IDs.',
     'fields' => array(
@@ -1794,3 +1825,49 @@ function system_update_8203() {
     ->set('logging', 1)
     ->save(TRUE);
 }
+
+/**
+ * @addtogroup updates-8.3.0
+ * @{
+ */
+
+/**
+ * Install key_value_sorted schema.
+ */
+function system_update_8300() {
+  $table = array(
+    'description' => 'Key-value list storage table.',
+    'fields' => array(
+      'collection' => array(
+        'description' => 'A named collection of key and value pairs.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      // KEY is an SQL reserved word, so use 'name' as the key's field name.
+      'name' => array(
+        'description' => 'The index or score key for the value.',
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'size' => 'big',
+      ),
+      'value' => array(
+        'description' => 'The value.',
+        'type' => 'blob',
+        'not null' => TRUE,
+        'size' => 'big',
+      ),
+    ),
+    'indexes' => array(
+      'collection_name' => array('collection', 'name'),
+      'name' => array('name'),
+    ),
+  );
+  \Drupal::database()->schema()->createTable('key_value_sorted', $table);
+}
+
+/**
+ * @} End of "addtogroup updates-8.3.0".
+ */
diff --git a/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageSortedSetTest.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageSortedSetTest.php
new file mode 100644
index 0000000..d06d2eb
--- /dev/null
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageSortedSetTest.php
@@ -0,0 +1,120 @@
+<?php
+
+namespace Drupal\KernelTests\Core\KeyValueStore;
+
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests the sorted set key-value database storage.
+ *
+ * @group KeyValueStore
+ */
+class DatabaseStorageSortedSetTest extends KernelTestBase {
+
+
+  static public $modules = array('system', 'serialization');
+
+  /**
+   * @var string
+   */
+  protected $collection;
+
+  /**
+   * @var \Drupal\Component\Serialization\SerializationInterface
+   */
+  protected $serializer;
+
+  /**
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * @var \Drupal\Core\KeyValueStore\KeyValueStoreSortedSetInterface
+   */
+  protected $store;
+
+  public function setUp() {
+    parent::setUp();
+    $this->installSchema('system', array('key_value_sorted'));
+
+    $this->collection = $this->randomMachineName();
+    $this->serializer = \Drupal::service('serialization.phpserialize');
+    $this->connection = \Drupal::service('database');
+    $this->store = \Drupal::service('keyvalue.sorted_set')->get($this->collection);
+  }
+
+  public function assertPairs($expected_pairs) {
+    $result = $this->connection->select('key_value_sorted', 't')
+      ->fields('t', array('name', 'value'))
+      ->condition('collection', $this->collection)
+      ->condition('name', array_keys($expected_pairs), 'IN')
+      ->execute()
+      ->fetchAllAssoc('name');
+
+    $expected_count = count($expected_pairs);
+    $this->assertSame(count($result), $expected_count, "Query affected $expected_count records.");
+    foreach ($expected_pairs as $key => $value) {
+      $this->assertSame($this->serializer->decode($result[$key]->value), $value, "Key $key have value $value");
+    }
+  }
+
+  public function assertRecords($expected, $message = NULL) {
+    $count = $this->connection->select('key_value_sorted', 't')
+      ->fields('t')
+      ->condition('collection', $this->collection)
+      ->countQuery()
+      ->execute()
+      ->fetchField();
+    $this->assertEquals($expected, $count, $message ? $message : "There are $expected records.");
+  }
+
+  public function newKey() {
+    return (int) (microtime(TRUE) * 1000000);
+  }
+
+  public function testCalls() {
+    $key0 = $this->newKey();
+    $value0 = $this->randomMachineName();
+    $this->store->add($key0, $value0);
+    $this->assertPairs(array($key0 => $value0));
+
+    $key1 = $this->newKey();
+    $value1 = $this->randomMachineName();
+    $this->store->add($key1, $value1);
+    $this->assertPairs(array($key1 => $value1));
+
+    // Ensure it works to add sets with the same score.
+    $key2 = $this->newKey();
+    $value2 = $this->randomMachineName();
+    $value3 = $this->randomMachineName();
+    $value4 = $this->randomMachineName();
+    $this->store->addMultiple(array(
+      array($key2 => $value2),
+      array($key2 => $value3),
+      array($key2 => $value4),
+    ));
+
+    $count = $this->store->getCount();
+    $this->assertEquals(5, $count, 'The count method returned correct count.');
+
+    $value = $this->store->getRange($key1, $key2);
+    $this->assertSame($value, array($value1, $value2, $value3, $value4));
+
+    $new1 = $this->newKey();
+    $this->store->add($new1, $value1);
+
+    $value = $this->store->getRange($new1, $new1);
+    $this->assertSame($value, array($value1), 'Member was successfully updated.');
+    $this->assertRecords(5, 'Correct number of record in the collection after member update.');
+
+    $value = $this->store->getRange($key1, $key1);
+    $this->assertSame($value, array(), 'Non-existing range returned empty array.');
+
+    $max_score = $this->store->getMaxScore();
+    $this->assertEquals($max_score, $new1, 'The getMaxScore method returned correct score.');
+
+    $min_score = $this->store->getMinScore();
+    $this->assertEquals($min_score, $key0, 'The getMinScore method returned correct score.');
+  }
+}