diff --git a/core/lib/Drupal/Core/Cache/DatabaseBackend.php b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
index d0d8278..3a9fb78 100644
--- a/core/lib/Drupal/Core/Cache/DatabaseBackend.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
@@ -160,7 +160,9 @@ protected function prepareItem($cache, $allow_invalid) {
    * Implements Drupal\Core\Cache\CacheBackendInterface::set().
    */
   public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = array()) {
-    // Check if maximum expiration settings for cache bin is defined
+    // Check if maximum expiration settings for cache bin is defined. If set,
+    // enforce an upper limit for the expiration to allow for garbage
+    // collection.
     if (isset($this->configuration['max_expire']) && ($expire == Cache::PERMANENT || $expire > $this->configuration['max_expire'] + REQUEST_TIME)) {
       $expire = $this->configuration['max_expire'] + REQUEST_TIME;
     }
diff --git a/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php b/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php
index fd46b66..7b55e51 100644
--- a/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php
@@ -44,8 +44,8 @@ class DatabaseBackendFactory implements CacheFactoryInterface {
   function __construct(Connection $connection, CacheTagsChecksumInterface $checksum_provider) {
     $this->connection = $connection;
     $this->checksumProvider = $checksum_provider;
-    // Set cache_database settings from settings.php and if none is set use
-    // maximum expire for render bin for one week.
+    // Load settings and if not set, default to maximum expiration of the render
+    // cache bin in one week.
     $this->configuration = Settings::get('cache_database', ['render' => ['max_expire' => 86400 * 7]]);
   }
 
diff --git a/core/modules/system/src/Tests/Cache/DatabaseBackendUnitTest.php b/core/modules/system/src/Tests/Cache/DatabaseBackendUnitTest.php
index a5f8ff7..f88ba11 100644
--- a/core/modules/system/src/Tests/Cache/DatabaseBackendUnitTest.php
+++ b/core/modules/system/src/Tests/Cache/DatabaseBackendUnitTest.php
@@ -53,23 +53,49 @@ public function testSetGet() {
     $this->assertIdentical($cached_value_short, $backend->get($cid_short)->data, "Backend contains the correct value for short, non-ASCII cache id.");
   }
 
-  public function testCacheBinExpiration(){
+  public function testCacheBinExpiration() {
     $configuration = ['max_expire' => 2800];
     $backend = new DatabaseBackend($this->container->get('database'), $this->container->get('cache_tags.invalidator.checksum'), 'render', $configuration);
+
     $backend->set('test_cache1', 'foo');
     $cached = $backend->get('test_cache1');
     $this->assertIdentical($cached->expire, (string) (REQUEST_TIME + 2800), 'Maximum cache expire time is correct.');
 
-    $configuration = ['max_expire' => 2800];
-    $backend = new DatabaseBackend($this->container->get('database'), $this->container->get('cache_tags.invalidator.checksum'), 'render', $configuration);
     $backend->set('test_cache2', 'foo', REQUEST_TIME + 2799);
     $cached = $backend->get('test_cache2');
     $this->assertIdentical($cached->expire, (string) (REQUEST_TIME + 2799), 'Maximum cache expire time is correct.');
 
+    $backend->set('test_cache3', 'foo', REQUEST_TIME + 2801);
+    $cached = $backend->get('test_cache3');
+    $this->assertIdentical($cached->expire, (string) (REQUEST_TIME + 2800), 'Maximum cache expire time is not exceeded.');
+  }
+
+  public function testCacheBinExpirationSetMultiple() {
     $configuration = ['max_expire' => 2800];
     $backend = new DatabaseBackend($this->container->get('database'), $this->container->get('cache_tags.invalidator.checksum'), 'render', $configuration);
-    $backend->set('test_cache3', 'foo', REQUEST_TIME + 2801);
+
+    $backend->setMultiple([
+      'test_cache1' => [
+        'data' => 'foo',
+      ],
+      'test_cache2' => [
+        'data' => 'foo',
+        'expire' => REQUEST_TIME + 2799,
+      ],
+      'test_cache3' => [
+        'data' => 'foo',
+        'expire' => REQUEST_TIME + 2801,
+      ],
+    ]);
+
+    $cached = $backend->get('test_cache1');
+    $this->assertIdentical($cached->expire, (string) (REQUEST_TIME + 2800), 'Maximum cache expire time is correct.');
+
+    $cached = $backend->get('test_cache2');
+    $this->assertIdentical($cached->expire, (string) (REQUEST_TIME + 2799), 'Maximum cache expire time is correct.');
+
     $cached = $backend->get('test_cache3');
     $this->assertIdentical($cached->expire, (string) (REQUEST_TIME + 2800), 'Maximum cache expire time is not exceeded.');
   }
+
 }
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index b905a11..3777cf0 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -693,9 +693,15 @@
 # }
 
 /**
- * Per-bin database backend configuration
- *
- * Use this setting to set the maximum cache expiration time for a specific
- * cache bin in the database.
- */
-$settings['cache_database']['render']['max_expire'] = 86400 * 7;
+ * Per-bin database backend configuration.
+ *
+ * Configure settings for database backend. Available settings are:
+ * - max_expire: Specify the maximum expiry for an individual cache item in the
+ *   selected bin. Some cache bins can get very big and persistent cache entries
+ *   are never removed. Setting this value will allow them to be garbage
+ *   collected after the configured time, and will need to be rebuilt if the
+ *   item is requested again.
+ */
+$settings['cache_database']['render'] = [
+  'max_expire' => 86400 * 7,
+];