Patch for Magento's database backend

Varien_Cache_Backend_Database.patch

Index: lib/Varien/Cache/Backend/Database.php
===================================================================
--- lib/Varien/Cache/Backend/Database.php	(revision 63515)
+++ lib/Varien/Cache/Backend/Database.php	(working copy)
@@ -224,6 +224,7 @@
         if ($this->_options['store_data']) {
             $adapter = $this->_getAdapter();
             $result = $adapter->delete($this->_getDataTable(), array('id=?'=>$id));
+            $tagResult = $adapter->delete($this->_getTagsTable(), array('cache_id=?' => $id));
             return $result;
         } else {
             return false;
@@ -261,10 +262,7 @@
                 break;
             case Zend_Cache::CLEANING_MODE_OLD:
                 if ($this->_options['store_data']) {
-                    $result = $adapter->delete($this->_getDataTable(), array(
-                        'expire_time>' => 0,
-                        'expire_time<=' => time()
-                    ));
+                    $result = $this->_cleanOld();
                 } else {
                     $result = true;
                 }
@@ -281,7 +279,46 @@
 
         return $result;
     }
+    
+    /**
+     * Clean old cache records and related cache tag records
+     * 
+     * @return boolean true if no problem
+     */
+    protected function _cleanOld() 
+    {
+        $time = time();
+        $adapter = $this->_getAdapter();
+        
+        // get all expired cache records
+        $select = $adapter->select()
+                ->from($this->_getDataTable(), 'id')
+                ->where('expire_time>?', 0)
+                ->where('expire_time<=?', $time);
+        $stm = $adapter->query($select);
 
+        // delete attached cache tags
+        $ids = array();
+        while (($row = $stm->fetch()) == true) {
+            $ids[] = $row['id'];
+            if (count($ids) > 100) {
+                $adapter->delete($this->_getTagsTable(), array('cache_id IN (?)' => $ids));
+                $ids = array();
+            }
+        }
+        if (!empty($ids)) {
+            $adapter->delete($this->_getTagsTable(), array('cache_id IN (?)' => $ids));
+        }
+
+        // delete actual cache records
+        $result = $adapter->delete($this->_getDataTable(), array(
+            'expire_time>?' => 0,
+            'expire_time<=?' => $time
+        ));
+
+        return $result;
+    }
+
     /**
      * Return an array of stored cache ids
      *
@@ -416,7 +453,7 @@
             return $this->_getAdapter()->update(
                 $this->_getDataTable(),
                 array('expire_time'=>new Zend_Db_Expr('expire_time+'.$extraLifetime)),
-                array('id=?'=>$id, 'expire_time = 0 OR expire_time>'=>time())
+                array('id=?'=>$id, 'expire_time = 0 OR expire_time>?'=>time())
             );
         } else {
             return true;