diff --git a/framework/yii/caching/GroupDependency.php b/framework/yii/caching/GroupDependency.php
index be77344..af07d8a 100644
--- a/framework/yii/caching/GroupDependency.php
+++ b/framework/yii/caching/GroupDependency.php
@@ -42,11 +42,11 @@ class GroupDependency extends Dependency
 	 */
 	protected function generateDependencyData($cache)
 	{
-		if ($cache->get(array(__CLASS__, $this->group)) === false) {
-			// If the cutoff timestamp is not initialized or is swapped out of the cache, we need to set it.
-			$this->invalidate($cache, array(__CLASS__, $this->group));
+		$version = $cache->get(array(__CLASS__, $this->group));
+		if ($version === false) {
+			$version = $this->invalidate($cache, array(__CLASS__, $this->group));
 		}
-		return microtime(true);
+		return $version;
 	}
 
 	/**
@@ -56,17 +56,20 @@ class GroupDependency extends Dependency
 	 */
 	public function getHasChanged($cache)
 	{
-		$time = $cache->get(array(__CLASS__, $this->group));
-		return $time === false || $time > $this->data;
+		$version = $cache->get(array(__CLASS__, $this->group));
+		return $version === false || $version !== $this->data;
 	}
 
 	/**
 	 * Invalidates all of the cached data items that have the same [[group]].
 	 * @param Cache $cache the cache component that caches the data items
 	 * @param string $group the group name
+	 * @return string the current version number
 	 */
 	public static function invalidate($cache, $group)
 	{
-		$cache->set(array(__CLASS__, $group), microtime(true));
+		$version = microtime();
+		$cache->set(array(__CLASS__, $group), $version);
+		return $version;
 	}
 }
diff --git a/framework/yii/db/Schema.php b/framework/yii/db/Schema.php
index c961244..6ae9ab7 100644
--- a/framework/yii/db/Schema.php
+++ b/framework/yii/db/Schema.php
@@ -11,6 +11,7 @@ use Yii;
 use yii\base\NotSupportedException;
 use yii\base\InvalidCallException;
 use yii\caching\Cache;
+use yii\caching\GroupDependency;
 
 /**
  * Schema is the base class for concrete DBMS-specific schema classes.
@@ -93,7 +94,7 @@ abstract class Schema extends \yii\base\Object
 				if ($refresh || ($table = $cache->get($key)) === false) {
 					$table = $this->loadTableSchema($realName);
 					if ($table !== null) {
-						$cache->set($key, $table, $db->schemaCacheDuration);
+						$cache->set($key, $table, $db->schemaCacheDuration, new GroupDependency($this->getCacheGroup()));
 					}
 				}
 				return $this->_tables[$name] = $table;
@@ -107,7 +108,7 @@ abstract class Schema extends \yii\base\Object
 	 * @param string $name the table name
 	 * @return mixed the cache key
 	 */
-	public function getCacheKey($name)
+	protected function getCacheKey($name)
 	{
 		return array(
 			__CLASS__,
@@ -118,6 +119,20 @@ abstract class Schema extends \yii\base\Object
 	}
 
 	/**
+	 * Returns the cache group name.
+	 * This allows [[refresh()]] to invalidate all cached table schemas.
+	 * @return string the cache group name
+	 */
+	protected function getCacheGroup()
+	{
+		return md5(serialize(array(
+			__CLASS__,
+			$this->db->dsn,
+			$this->db->username,
+		)));
+	}
+
+	/**
 	 * Returns the metadata for all tables in the database.
 	 * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema name.
 	 * @param boolean $refresh whether to fetch the latest available table schemas. If this is false,
@@ -176,9 +191,7 @@ abstract class Schema extends \yii\base\Object
 		/** @var $cache Cache */
 		$cache = is_string($this->db->schemaCache) ? Yii::$app->getComponent($this->db->schemaCache) : $this->db->schemaCache;
 		if ($this->db->enableSchemaCache && $cache instanceof Cache) {
-			foreach ($this->_tables as $name => $table) {
-				$cache->delete($this->getCacheKey($name));
-			}
+			GroupDependency::invalidate($cache, $this->getCacheGroup());
 		}
 		$this->_tableNames = array();
 		$this->_tables = array();