+ {
+ return array_keys($this->keyTypes());
+ }
+
+ /**
+ * return key definitions for Memcached_DataObject
+ *
+ * Our caching system uses the same key definitions, but uses a different
+ * method to get them. This key information is used to store and clear
+ * cached data, so be sure to list any key that will be used for static
+ * lookups.
+ *
+ * @return array associative array of key definitions, field name to type:
+ * 'K' for primary key: for compound keys, add an entry for each component;
+ * 'U' for unique keys: compound keys are not well supported here.
+ */
+
+ function keyTypes()